Sorry, but like Jason mentioned, it's kind of impossible to answer your question about tankmate compatibility without knowing the ID of the pike. There are all different types ranging from dwarfs to 15" fish, and they range from mildly aggressive to really aggressive. Pictures would help to ID them.
If you're unsure, put them in a tank alone for now with lots of cover so that they can hide from each other. They may very quickly kill one another if they're not paired off.
I will say that I had some 5" lugubris-type pikes (possibly C. johanna) in my 210 gallon with large adult severums and a parrot cichlid (psittacus), and the pikes were quickly becoming the dominant fish. They would attack and chase my severums. A pike that's double that size would probably easily beat the crap out of your severums.