Oops, that was me. Also, I checked the wiki again, and I realized that her full name is actually Blisstina "Bliss" Francesca Francia Mariam Alicia Utonium [I am not kidding you].
She is taller because she is a teenager [eight years age gap at stretch], and she was made when Professor Utonium got in a fight with someone named Professor Plutonium [???] when he made 'The Perfect Little Boy'.
Edit, she also has a tiny pet elephant apparently. Here's a clip I found. https://www.youtube.com/watch?v=wJzcmoTBaTE Her voice actor might be a bit too deep for her too, considering it is Marceline's. Classic Mary Sue backstory.

You can, but you need a race to be racist against.

True, I guess 'because Tumblr [insert literally anything here: optional]' is a valid argument.

They likely mean mentally. For instance, I assume that knowing that someone [even if it's a significant other, and it's considered 'normal' for a vampire to do so] watches you in your sleep could cause paranoia, or maybe manipulation.

I believe that that is Ruby [something like that] from RWBY, a series that is made by Roosterteeth if I remember correctly. I don't know why she's there, though.