[Opinions] Sebastian and Savannah
Replies
Out of the context of your story, these two names are not related in my mind at all. They happen to both have three syllables and begin with "S" but that could be coincidence. Whether I would suspect more than coincidence within the context of your story, I can't say.
Aside from them starting with the same letter and both having a lot of letters, I don't think that they seem all that similar. I actually wouldn't have thought to pair them together, so no, I don't find the names too obvious.