The best way to develop a common bond when working with other musicians is to first, as mentioned above, find a common thread between you. Most times, this involves playing songs you both know and enjoy. I noticed you mentioned not having an interest in learning other people's material. I would not recommend this approach. Without input, there is no output. If you put work into playing some common songs and progressions together, the both of you with time will find a common ground and will have a ton of fun playing together.

A very common starting point with this is playing a 12 Bar Blues. Here is the form if you are unfamiliar with it;

12 Bar Blues in A

A7 - A7 - A7 - A7 - D7 - D7 - A7 - A7 - E7 - D7 - A7 - E7

You can play this over and over and over again and still find new and interesting ideas to mess with as a duo. Trust me, the journey through playing the blues never ends. You can play your pentatonic and blues scales and he can simply play the root notes with a nice groove. You can than sneak some theory in there by "encouraging" him to play other notes in these chords. Here are the notes in each of these chords;

A7 - A, C#, E, G
D7 - D, F#, A, C
E7 - E, G#, B, D

He can do no wrong by playing these notes while you solo and play the chords along with him. This is a great way to start learning how to play together.

Again, I strongly recommend putting some songs together that you both enjoy listening too that both of you could easily learn. The key is is to learn how to play and interact together, as every musician is different even if they are playing the same instruments. Best of luck and hopefully this helps.
:D