The first is Tony and i think phil.
Tony is into BDSM but his partner abuses him. Phil? Finds out and looks after him. Lays down the law and says any prospective partner must be checked out and approved by JARVIS first. The end was the person liking Tony so much that they submit themselves to JARVIS approval.
The second is a Loki and Steve? fic. The person works out that loki only kills on 1 day a year and the number goes up by 1 esch year. Works out that this is his birthday and he kills because no one remembers. They find where he is living and take him a cake the day before. There is an attack the next day but no deaths. A relationship then develops.
FOUND - details in the comments.
Hope you guys can help as my search so far have been unsuccessful.