With the many possibilities for who Teela's father might be and the many origins of Teela, what are your thoughts or headcanons of who her father is or does she or should she have (biological) one in your opinion?
Who Teela's biological father is doesn't really matter. Duncan is the person who raised her, he should be the only parent that matters.
Most newer iterations make Duncan Teela's biological father and I guess I'm okay with that. It doesn't really change anything fundamental about Teela's character, their relationship, or their roles in the story.
Personally, I prefer Duncan being Teela's adopted father like he was in Filmation.
May I assume this Ask was prompted by my fan fic where Tri-Klops pretends to be Teela's biological father in order to spring Trap Jaw from prison? That idea actually came from the MotU discord server I'm on. We were specifically talking about in 200X in the episode that shows the Sorceress' romance with Teela's father, he's never named, and his face is mostly covered in bandages. According to the 200X show bible, Fisto was meant to be Teela's biological father but the series was cancelled before that reveal, so with the clues that got dropped in the episode that did get made, Teela's father could be any human male character in the right age bracket. Yeah, Duncan or Fisto were the obvious choices, but Tri-Klops also fit and it struck us then that pretending to be Teela's long lost father could be a pretext for sneaking into the Palace of Eternos