One possiblity is Shaman, since Alpha Flight likely won't be making an appearance in anyone else's movies.Perhaps somebody decides to investigate the case of Peter's mysterious disappearance (complete with ramblings from his guilt-filled grandfather) at the same time Quill Sr.
In-show, it would make sense for him to choose the name "Paladin" as a reflection of the "true hero" he really wants to be, but in practice, he's still an aimless merc whose loyalty is up for grabs.
Bonus points for possibly using an old ICER as the MCU version of Paladin's "Stun-Gun".
Maybe found by SHIELD and made an agent when they discovered what he was. It would also explain why, when confronting Loki, he hesitated to use the Thorbuster instead of using it right away.
It would also explain why he's so loyal to Fury - Fury reminds him of Grandpa. Randolph says that he didn't know Thor and that he was just a mason, but maybe movie!
It partially explains her quest to find unique people: because she's also looking for her family, same as Skye.
Paladin in the comics is a highly skilled mercenary who is shown to work with heroes just as often as he works with villains.
He survived being stabbed because his Soul Gem was unharmed. The higher-ups don't want him to know since everyone else who's been informed of the true nature of the Soul Gem has had a freakout.
Combining this a bit with the "Coulson is psychic" guess in the "Other" section, the reason that he is so aware of everything on seemingly so little clues is because something about his wish gave him psychic powers or he has just figured out how to use magic to see these things.
nobody in the comics actually knows what Paladin's real name is.
He's given it as "Paul Denning" before, but this is suggested to be a fake name.
arrives to ask where the hell that son he's been expecting is.