For my own reference and perhaps others' interest, this entry is to keep track of Sky's friendships/relationships. If you think I've forgotten your character, please comment and I'll add them.
[This list is incomplete and ever-expanding. Last modified: 8/5/10]
SPECIAL
galacticgeisha (Inara Serra, Firefly/Serenity) - Formerly known as Companion. Sky's girlfriend and the love of his life. She and Sky were not well-acquainted until she bid on and won him in Rose (Kitty)'s bachelor auction in February 2009. They greatly enjoyed the date and developed a friendship that soon progressed into something more on Sky's part, and complicated feelings on hers. However, a problem arose with the fact that, while Inara did like spending time with him, she also had romantic and sexual feelings toward Wolverine. Both of them pinged her for people she dearly cared about from her past- Wolverine for Mal and Sky for Simon (who, incidentally, would arrive in the Sphere as Will shortly after Sky and Inara began their romantic relationship in earnest). The triangle continued for some months, with all sides reluctant to talk about their feelings so as not to cause hurt and hardship for the others, until Sky accompanied Inara to Bubbles' charity ball in June. Shortly thereafter, Wolverine told her he felt he would make a better friend than lover, and Inara thus committed herself to Sky. Their mutual infatuation took some time to develop into true love, but Sky is now completely head-over-heels for her. Aside from this, he trusts her completely.
handy_psychic (Bridge Carson, Power Rangers S.P.D.) - Formerly known as Brooklyn. Bridge was the clearest person in Sky's first birth dream, and the two quickly rekindled the close friendship they had in their past life when reunited in Edensphere, even becoming roommates once again. Sky has a tolerance and patience for Bridge's quirks and habits that not everyone possesses, and Sky feels protective toward Bridge and a need to shelter him from the harsh realities of life in Edensphere as best he can. Bridge in turn tempers Sky's closed-offness and never lets him take himself too seriously. The two of them have had their fair share of tension in the past, however: Bridge often resents feeling like he has to do damage control when Sky has a temper outburst, Sky thinks Bridge needs to take care of himself better and grow up a little (which seems hypocritical given the fact that he also wants to protect Bridge from reality), and Bridge's unrequieted romantic feelings for Sky manifested in fits of jealousy and picking fights when he and Inara began dating. However, Bridge seems to have put his feelings to rest for good, and the future looks brighter for their friendship. The two aren't as close as they once were, but their bond is unbreakable.
redrobinhood (Jack Landors, Power Rangers S.P.D.) - Ghost and Sky can be summed up by this sentence: "Those two are more alike than they care to admit". They share the same relationship they did in their past- they are total opposites, they bicker, they argue, they sometimes hate each other, they are best friends and would die for one another without a second thought. It took some time for Sky to warm up to Ghost due to their personalities, but through their arguments and fights together, they became close. They also know they were both leaders and Red Rangers in the past, and Sky very much considers Ghost to be equal, as they're of similar minds in knowing that sometimes sacrifices have to be made for the greater good- even if they are the ones whose lives must be given.
pinkhairedchild (Kusajishi Yachiru, Bleach)- Previously known as Blood. Sky scoffed at Yachiru at first and still sometimes has no idea how to react around her due to her physically and mentally being a child. However, he acknowledges and admires her immense skill as a fighter and tries to treat her as an equal and as someone whose opinion matters to him, while secretly wishing that, like with Bridge, he could shelter her from reality. She has christened him with the nickname "Cloudy-hedgehog" due to the fact that he goes by both Sky and Spike, much to his chagrin (and secret pleasure).
felinemystique (Shihouin Yoruichi, Bleach) - As Captain of the Guard and someone who pings him for both Commander Cruger and Kat Manx, important mentor and authority figures from his past, Sky has an immense amount of respect for Bastet. He regards her as a dear friend and someone in whom he can put his trust completely without worrying it will be betrayed or taken advantage of. She also has a knack for not allowing him to wallow in self-pity for too long.
stonyfaced (Sam Vimes, Discworld) - Stoneface also pings Sky for Commander Cruger, much more strongly that Bastet does, and so looks up to him as a mentor and almost father-like figure as a result. Stoneface is also one of the few people who actively discourages Sky's temper problems and gets him to question his behavior on his own simply by virtue of being frank and knowing when to step away and stop feeding the fire. Sky hates the idea of ever letting him down.
POSITIVE
reckless_rebel (Tommy "Speed" Shepherd, Young Avengers) - Dash was one of the first people in the Sphere whom Sky spoke to and struck up a friendship with, and Sky is proud to call himself Dash's minion.
pimpcoatbankai (Kurosaki Ichigo, Bleach) - Sky and Blood were Toushi's guides when he was reborn into Edensphere with no memories of the place. He was happy to be able to connect with the young man during his second stay in Edensphere, as Toushi's temper outbursts and utter devotion to the cause of protecting his loved ones reminds Sky of himself, and he considers him to be a pretty good guy.
spandexisyouth (Maito Gai, Naruto) - While Youth seems goofy, naive and flippant at times, his devotion to his loved ones and commitment to always training his body, striving to become better, and ability to recover quickly from a fall are qualities Sky admires.
mythgravenblade (Cecil Harvey, Final Fantasy 4) - Paladin is Sky's teacher in swordsmanship and someone he respects for his gentleness and his willingness to help others.
Edgeworth (Justice)
Handmaiden
Kazahana
Cara
Reed
Target
NEUTRAL
pompous_today (Simon Tam, Firefly/Serenity) - Formerly known as Will. Sky and Simon have a passing aquaintance with one another due to their mutual relationships with Inara and Ghost. Sky comes across as cold and non-talkative to Simon, and Simon seems a tad too obsessed with his sister for Sky's tastes.
flenceburgsbest (Lezard Valeth, Valkyrie Profile) - Sky respects the work Lezard does as Head Medic, as well as the man's intelligence, but he is also wary of him.
Everyone else
NEGATIVE
None so far
GONE BUT NOT FORGOTTEN
kanin_gitarist (Toki Wartooth, Metalocalypse) - Kanin was one of the first people in the Sphere Spike befriended and got close to; he appreciated his trusting, friendly nature, and stood by him when he killed someone in October 2008. They shared a close relationship until Kanin disappeared in June 2009; his disappearance is still a sore spot, as Spike blames himself for it, and it's hard for him to talk about him.
silver_antlers (Harry Potter, Harry Potter) - Formerly known as Prongs. Something about Harry brings out Sky's protective instincts, and so he tends to think of and treat him as a little brother. He feels incredibly guilty that he is not able to stop Harry's loved ones from dying and disappearing, even though his friend does not blame him in the slightest, and is another person whom Sky wants to shelter from reality.
bubble_ditz (Galinda, Wicked) - Spike was not sure what to think about Bubbles. The two definitely got off on the wrong foot, as she thought he had an anger management problem, but as time went on they were able to be amicable toward one another, to the point where he even allowed her to make him an outfit for the Ball.
healing_death (Alanna of Trebond, Song of the Lioness) - Spike and Honor served on the Guard together and had a mutual respect for one another as warriors.
doctorears (The Ninth Doctor, Doctor Who) - Sky was Storm's Guide upon birth, and the two hit it off right away. He shared bits about his own past with Storm, who was curious as to how memories are seen.
surrendertoto (Elphaba, Wicked) - West was always very kind to Sky, and while he was not particularly close to her, he misses her.
sauntersthrough (Crowley, Good Omens) - Fallen was an older brother/mentor-type figure for Sky, and his brutal murder affected him deeply. He still thinks of and misses him on occasion.
sassyandpink (Sydney "Syd" Drew, Power Rangers S.P.D.) - Sky and Pinky definitely started off their relationship on a sour note; he was her Guide when she emerged and she got on his bad side right away when she expressed her opinion that he needed to lighten up. They were also unaware that they came from the same place until certain memories were revealed, and gradually mended their bad start through their mutual friendships with Bridge and Ghost. Her loss has affected Sky a lot more deeply than he even realizes.
blondsambitions (Skwisgaar Skwigelf, Metalocalypse) - Formerly known as Alexi. Sky and Skwisgaar were quite good friends during his first stay in the Sphere in spite of the fact that Skiwsgaar often got on his nerves; the fact that he was dating Kanin definitely boosted his status. Sky was quite saddened when he disappeared; when he came back with no memories of Edensphere, Sky kept him at arms' length, secretly and irrationally angry that he didn't bring Kanin back with him. However, the two slowly rebuilt their friendship.
inthecenterfold (Sha Gojyo, Saiyuki) - Sky and Smoke didn't have a very close relationship with each other even when he and Ghost were dating, though the two sparred a few times.
monoideist (Allelujah Haptism, Gundam 00) - Formerly known as Raise (and his other personality, Praise). Sky wanted a positive relationship with Raise, but was very wary of getting close to him due to Raise's evil alter-ego, Praise. When Raise came back as Dyad, with no memories of the Sphere and apparently without his other personality, Sky was not sure how to react how to him, considering that Praise had murdered Stoneface.
Drake
Renae
Scales