Something I want to do with ShinDig! is to have Shin develop several friendly rivalries, Pike here being the first of many.
The thing about these rivalries is the common ground and polar differences involved. For example, both Shin and Pike suffer from a curse, but manage to overcome or find a loophole in it. They use classic opposing elements, and vary greatly in shape, skill and choice of weaponry, though.
Pike is sort of a mentor to Shin, and sort of reflects what Shin can eventually become if he disciplines himself enough. What better role model than the guy that can beat you in his sleep(mostly because he sort of has to)?