Vincent is basically a god in his world (yes as incredibly unlikely as it may seem) and quite frankly I've never played such a powerful character and hopefully this will help me and you.
First let's just get into what the proxy of Romdeau's abilities are, along with his Achilles heel (because he was thankfully programmed with one).
Vincent is a proxy, and perhaps not just any proxy, but the first proxy. Proxies are gods of creation and death, but they are manmade gods. Thus while they may not have the omnipotence of other gods (though when Ergo Proxy had his memories he was aware of what the end would be like; this was either inherently programmed into him or he learned it in some way, but either way all the proxies seemed to know their ultimate fate was to annihilate and be annihilated) they still have a wide range of inhuman capabilities.
→ Their main god-like characteristic is that they posses what are called "Amrita" cells. This is what apparently makes a proxy a proxy. The cells are more or less immortal but can be destroyed by sunlight (mainly due to the fact proxies were not supposed to exist after the sky had cleared on Earth again). While a proxy can still become sick they can never die from an illness as their Amrita cells would eventually destroy it. (Vincent even survives a virus that kills a high rate of humans outside the dome without a vaccine due to his Amrita cells.) Their bodies are thus far more invulnerable than a human's. Vincent can survive falls from great heights, and wounds that be fatal for a human.
Proxies can kill one another, however. Either Vincent alone, or they all, posses an innate power to destroy Amrita cells. In Vincent at least it manifests as something like electrical energy from the eyes and mouth. He used this ability to kill Monad Proxy and Sennex Proxy. Though proxies were originally meant to be the only ones who could slay one another, Daedalus Yumeno developed what are called "FP" bullets. These bullets can destroy a proxy's Amrita cells if fired into a proxy's body.
Possibly the Amrita cells also give the following abilities, but Vincent has displayed them none the less as well:
☇Inhuman speed: Proxies can apparently move faster than the human eyes can see, and apparently for sustained periods of time.
☇Inhuman strength: It be hard to say exactly what their limit is, but proxies have been shown to leave dents in cement with their bare hands alone. They can also bend steel at least also with bare hands.
☇And together these mean inhuman agility. Proxies are ridiculously coordinated even at high speeds, able to dodge and flip in mid air.
☇Force field: They seem to be able to throw out a burst of energy from themselves that can at least shatter glass. This seems to flow like a shockwave from their body in one direction. It’s like a blast and not refined.
☇Limb regeneration: To prevent himself from being killed by a FP bullet Proxy One literally tore his arm off. The arm instantly regenerated within a matter of seconds. I would say this is limited to limbs however and not perhaps something like organs as a proxy that was shot in a chest with a FP bullet died quite quickly.
→Proxies are also given two forms: that of the god and that of a human. The change between the two forms seems to be intrinsically tied to the proxy's mental state. If Vincent is resistant to transforming the process is painful and slower, if he does not resist the change it's faster and easier for him. He's been shown to at least be able to move like a proxy while still a human, so he appears to only be partially "powered down" while human.
→Proxies also seem possess an ability to sense one another, even if they are in human form. Kazkis knew Vincent was a proxy, and in some way Vincent seems to have been drawn to the Monad inside of Re-l. (I don’t think even he knows how much this drew him however.)
→As a human, Vincent is apparently also a skilled mechanic.
∟ Though Amrita cells are the source of a proxy's god-like physiology they are also it's Achilles heel. As mentioned sunlight destroys the cells, or to be more exact it's likely the UV radiation is what kills the cells given that's what seems to be in the FP bullets. Monad's second clone literally burns up when exposed to unfiltered sunlight in the Earth's atmosphere.
In a setting with an unobstructed sky Vincent is going to inevitably experience weakening of his Amrita cells. Exposure to a clear sky in his proxy form would result in weakness, illness, and even burning. In his human he would be able to better withstand the sunlight as his physiology would be closer to a human's, but he would still feel what be tantamount to heat stroke if exposed to it for too long. These effects can be lessened by avoiding going out on clear days (filtration by cloud cover should be enough to lessen the effect to a safe level), and of course staying in the shade.
There is a problem however given how indestructible he really seems to be. Unless a character can indeed utilize UV radiation in some way to break down his Amrita cells (and Vincent himself has this ability to use against other proxies) he's going to be able to recover. It may take a long time, but he was genetically engineered to last as long as the Proxy Project was needed and that turned out to be thousands of years.
So with that in mind here are general permissions:
[ OOC ]
Backtagging: Like a boss. Seriously I am dependent on it.
Thread-hopping: Please and thank you, as long as it's logical to do so.
Fourth-walling: Unlikely for this character, but I would prefer not unless it's an event.
[ IC ]
Hugging or kissing this character: Unless you're Pino or Re-l, it make him uncomfortable but he'd tolerate it; either sex.
Fighting: Hopefully we already covered that. But plotting would probably be needed just because he is a god-like being.
Friendship: Yes! Vincent is awkward and shy but he does want friends.
Romance and sex: Why would you even-? Unless you're Re-l, it's not likely. He's not really inclined towards flirting, (his head is THICK okay) and while he'll be nice he's also more than likely be very uncomfortable with being approached in that manner.
Telepathic and Psychic powers: OH my god...it's like any human psychic that managed to touch a proxy's mind would have theirs blown. Other proxies tried to touch Ergo's mind, and were defeated rather easily by him. So his mind is pretty much untouchable unless your character is also a god-like being.
The thing is though he's not really conscious of the fact he has this impenetrable mind (like he's not conscious about most of his abilities). So he's not going to make an effort to conceal this fact. And personally if I was a psychic and the derp down the hall had a mind I couldn't touch; I be just a wee bit suspicious. So feel free to play off of that.
I like to treat each psychic on a case by case basis however, as there is evidence he can be taken in by illusions, to a point anyway. Possibly other forms of psychic attack may or may not work against him. So just, ask.
Magic abilities: Again if your character can sense darkness or something of the like, Vincent probably still has a shadow of it as he still has a function as an "agent of death" in his world. By contrast he was also a creator god at first, and still has some domain over humans so he may have light present in him as well. Feel free to have them sense he's actually a very powerful being in his human form if you think they could. Just ask for expansion if you like too.
Anything else: Just ask, I just hope I gave you an idea what you could expect with his abilities. Though for the most part...they probably won't even come up. He's actually not all that aggressive until people he cares about are threatened. :|