User blog comment:B214/Volume 22 spoilers/@comment-74.173.162.168-20161030032159/@comment-29963364-20161030124607

Again. Most likely.

Azazel, and to a lesser extent, Sirzechs, were Issei's only guides in regards to the "political aspects" of the supernatural world. They made sure Issei didn't do anything too crazy and prevented anything too bad from happening to him.

Azazel was his mentor and Sirzech was his role model (although their craziness did make him cringe more often than not). So now that Issei has lost them both, and just when he obtained power that rivals the Gods, and the rank of High-Class Devil, he's become an extremely unpredictable and dangerous "wild-card" in the supernatural world.

He and Vali are basically becoming the second Ddraig and Albion. And we all remember what happened when those two were left to their own devices.