Part 1/11 of my HP/Die Hard Hans & Severus are twins story that somehow turned into a HG/SS soulmates / soul marks story is up:
https://www.fanfiction.net/s/14042291/1/It-Always-Goes-To-Shit https://archiveofourown.org/works/37257457/chapters/92958343 I should say this one is rated M for language (with the title itself having Shit in it I decided to go with M)
Summary: What if Hans Gruber and Severus Snape were twins? What if the events in Die Hard were in part an attempt to get Severus away from wizarding Britain before Voldemort’s seemingly imminent return? What if Severus had to deal with the potential of Voldemort’s return and teaching Harry Potter on top of mourning his brother’s death? What if he discovered the birthmark he's had is in fact a soul mark?