Sanguine was a healer with a blood control power. He could draw blood out of people, do something to it - Taylor - speculated he was cleaning it - and put it back in. He could create enormous blood clots the size of fists to cover people's wounds.
He distinguished himself during the oil-rig battle by using his abilities to provide needed first aid to injured capes.
During the invasion of Cauldron's Base Sanguine was one of the Irregulers who despaired in the fight against Zion and tried to take more immediate vengeance against the clandestine organization that made him into a monster. 
↑ 4.04.14.2Sanguine was tending to two injured. Not Irregulars, but not capes I recognized either. The boy had hair and skin with a texture and color like clotted blood. The injured had blood piled and crusted over their wounds, scabs bigger than my hand. Or my claw.
“Might get a few more recruits,” Sanguine said, not looking up from the wounded. He had hands extended to two different wounds on one individual, and was drawing blood into one hand and letting it snake out of the other, flowing into the wound. Was he cleaning it?--Excerpt from Extinction 27.5
↑“I’ve spent years like this,” Gully said. “It’s not just me, either. There’re others. Weld…”
“Weld and Hunch, Gentle Giant and Sanguine,” Gully said. “And the others who weren’t even lucky enough to find the Wards or the Protectorate before they found themselves in trouble. It’s not just for me. We need to know for them.” - Excerpt from Scourge 19.4
↑"Hey, Weld. Boss-man. Enough talking?” A boy with red skin asked.
Weld half-turned to look at the crowd. “What’s the problem?”
“This is kinda fucked. You’re talking to her like she’s a buddy.”
“No,” Weld said. When he looked at her, his steel eyes were cold. “Not a buddy.”