Leech

"Archibald Leech is the secret weapon Control unleashes when the fabric of reality tears and alien mathematics leak into our world. Control wields him like a barely understood instrument, because Leech can see through the curtain, and it's enough to drive a man mad. But now his relationship with Control is slowly disintegrating as his need to create a safe home for his volatile and hard-drinking wife increases. Unfortunately, people in Leech's line of work don't retire so easily--not when he's pitting himself against doppelgangers, demigods, and whatever the hell else might be waiting in line to give him a bad day."--Publisher's description.