Do the names Phoenix and Sephina clash?! (For a book)?

The main character in my book is called Alaska, and she falls in love with a guy called Lincoln. Both of the characters have second identities which they are using when they first meet. Alaska's second identity is Sephina (or "Sephy"), and I'm trying to think of Lincoln's second identity. At the moment I'm thinking Phoenix but I'm not sure if it goes with Sephina/Sephy? I dunno if the repeated 'ph' is good together?
What do you think?
What other names could I use for Lincoln's second identity (I want something unusual, like the rest of the names)
If i DO go with Phoenix, what do you think of the nickname "Phox" (pronounced like fox).

Thanks!!