Cyric has been imprisoned by the other gods for the murder committed. This is the theme of my campaign.
As there is not much info on Cyric out there, I use Vecna for all my inspiration for what Cyric is like. And indeed, he aspires to take Mystras place.
His loyal servant and alchemist extroadinaire, Strahd Von Zarovich, has freed him recently right beneath the gods noses but the process has left himself damaged, with a shard of Mystra lodged in his brain. He has sent Cyric to another virtual prison in the Shadowfell and has lost all memory of his personality and mission, heavily influenced by the shard of the fallen goddess. If the PCs remove it (lets hope), he will remember exactly who, why and what he is.
Meanwhile Cyrics other minions search for the other shards of Mystra scattered throughout the scarplagued lands. Eventually he will begin piecing her together into himself (her eye in his own empty socket etc) until he looks like a living shattered mirror, and ascends to her former position of power as lord over all magic.
Only the evil god, Zehir is aware of what moves in the darkness and has allied with the pCs against Cyric. However any help they lend Cyric, Zehir will surely twist to benefit his own dark, personal ambitions. The Pcs have already incarnated him with one of the shards of Mystra and made a pact to serve him in return for personal power.
Lots of people hate the new realms, but I've found the shattered realms a very cool place to build an epic story.