The reborn character can be developed by exploring their initial reactions to being reborn in this Homelander - centric world. Are they excited to be part of this universe or terrified? Their reaction can shape their character arc. Also, give them a moral code. If they are trying to change Homelander, what are the lines they won't cross? In terms of appearance, it can be something that reflects their personality or their new - found purpose. For example, if they are a symbol of hope against Homelander's tyranny, they could have a bright and heroic - looking appearance. Their speech and mannerisms should also be distinct. If they are from a different time or place, that should show in how they talk and act around others, especially Homelander.
One idea could be exploring Homelander's childhood from the perspective of the reborn character. Maybe the character tries to prevent Homelander from becoming the villain he is. Another plot could involve the reborn character using their knowledge of Homelander's weaknesses to try and control him for the greater good. And a third could be that the character is reborn as Homelander himself and has to deal with the internal struggle of his powers and his public image.
Definitely. The comic version of Homelander is portrayed as having greater strength and capabilities. This is evident in his confrontations and the scale of his power displays throughout the comic series.