Decay said:
Putting aside everything else, it's super messed up because you'd literally share the same parents.
It's probably worse, but at the minimum, exactly as bad as hooking up with your sister
Loki was adopted. Could be that Odin just happened across a different orphan in a different timeline and raised her as the God of Mischief. Growing up in Thor's shadow still drives them to be crazy, narcissistic a-holes.
We know that Thor is 1500 years old, they have never really mentioned anything about Loki, though we know that when they were both children, they used to do "get help" and loki pretended to be snake once and stabbed Thor, so he is probably around the same age.
we don't really know how old sylvie is. how long do asgardians (or orphaned frost giants) stay in adolescent form? Is Sylvie 12 in the flashback or 100? Has she been running from the TVA for 1,000 years, or is she like 50 right now since time is irrelevant when you are time traveling?
anyways, maybe there are a few multiple timelines that are allowed to exist, so long as they reach a set end goal. Male or female, loki is supposed to be the big bad that brings the avengers together. In this particular case, Sylvie is playing with toys by herself, but instead of ruling over the viking action figures, she plays the hero that saves asgard, which causes a nexus event that creates a good loki. TVA needs a bad loki, so she is pruned.