The faces of
Zell - here
Ultimecia - here
Well, the graphic designer who designed these characters must have a first thought - both of the characters were linked at some point (in blood, maybe?). The thought is then just meaningless now because of changes to the story - there's no relationship or anything about between Zell and Ultimecia in the game anymore.
But this could be flawed, Squall and other members didn't know anything about Time Compression , so could it be a possibility that they didn't know about the link between Zell and Ultimecia too? They have never been bothered to find out about that because it's not really important, all of thier minds were always focused on how to beat Time Compression, saving Rinoa, etc.
concluding...
- Both of thier faces' tattoos match the resemblance of each other (not exactly same but very similar).
- As I recall from the game, there's nobody else who has tattoos on thier faces, apart from Zell and Ultimecia. A bit suspicious? I think so.
If the whole thing is just a pure coincidence that has nothing to do with anything then there must have a reason why the graphic designer made similar tattoos for both characters, that designer must had had some thoughts. I seriously don't think that I'd make things that are similar to each other in a game (well maybe apart from the characters' sizes, backgrounds, etc.) but tattoos only on two characters? No way.
Sooo... there's a possibility that Zell and Ultimecia are related in some sort, they just don't know it in the game
But I don't know if tattoos is the right word to use.
When Zell was born, did he recieve tattoos from his genes or got them from a shop? What about Ultimecia? If they got them off thier genes, then that must be something. If both of them got them from a shop, then they have the same common interest. Although...I doubt Ultimecia being a god (having power of time compression) would have gone to a shop and get the tattoos... that's just fishy.