Meaning of sentence

The writer is a cannibal and wants to eat the guy's heart.

You're confusing me further. The speaker is a gentleman.

The expression "after my own heart" is an idiomatic expression and cannot be understood in a literal sense only.

It commonly refers to a person whose character, personality, perspectives, opinions, and especially preferences are very compatible and agreeable with one's own ways of thinking and seeing things.

The expression is generally used in connection with the emotions, not so much matters of the intellect. It is similar to "a like-minded person".

Here's another example of usage:

Said by a seafood lover: "The moment Brunhilde lifted her fork and devoured a pile of pickled herring, I knew she was a person after my own heart."

Thanks. Aa.