Coco Marchand is a supporting character and was hired as a personal assistant to Eldritch Palmer, shortly after his head of security and long time bodyguard Reggie Fitzwilliam quit, perhaps as a replacement. She is not in the novels.
Little to nothing is known about Coco, other than that prior to her involvings with Palmer, she was a model for 5 years, but left that career after she became involved with "bad people." The way she feels about Palmer isn't quite clear, either. She is either covertly manipulating him to give into his humanity, she's manipulating him to further her own, personal gains, whatever they may be, she is actually falling for him, or she is clueless as to what's going on, even in regards to herself.
Coco decides to leave Eldritch not long after being employed by him, as she was angry and upset about being left in the dark about too many things, particularly Eldritch's involvement with the Strigoi. Palmer is able to apologize, and she seems to give him a second chance, since she believes his explanation that he has never experienced love while wheelchair-bound.
Coco is hit by the bullet that was intended for Eldritch and receives immediate medical attention, but she is left in a vegetable-like state. Palmer, overcome with grief and anger, demands that Eichhorst pass a message on to the Master, threatening that he will stop everything they have been working for unless Coco is saved and restored.
The Master complies, saving Coco by giving her the White. She wakes up immediately, witnessing him in the body of Gabriel Bolivar before he leaves with superhuman celerity, the likes of which no other being has been seen capable of.
Under Coco's influence, Palmer rescinds his financial backing so Eichhorst could not acquire the Occido Lumen. Eichhorst arrives at Stoneheart headquarter's to announce that his betrayal will have consequences. The Master appears moments later and a presumptuous and fiesty Palmer high-stakes gamble seems to pay off when the Master assures him that the details of the arrangement have not been changed. The Master then proceeds to feed on Coco, thus delivering "immortality" and the "white" to Palmer in a twisted way. Instead of letting Coco turn into a Strigoi, Palmer kills her and removes her heart while wearing gloves, so as to protect himself from infection just as Setrakian once did with his wife. Coco's death is likely the first time Palmer had to experience the loss of a loved one in an unusually tragic way, and the effects of this on his collaboration with the Master and Eichhorst have yet to be shown. However, after Coco's death, Palmer has been seen to become increasingly irritable and angry towards Eichhorst and the Master, more so than before.
While only on the show temporarily, and never having been introduced in the books, Coco made a significant impact, especially on Palmer. This speaks volumes about her character, considering she appears as more of a side character for Palmer than anything else.
Coco is portrayed as a very vibrant, likable character with an upbeat attitude. Despite only having just met Palmer, she quickly becomes more than just an assistant to him. Whenever in the presence of Eichhorst, she becomes guarded due to Eichhorst's mannerisms and the way in which he speaks to Palmer. She is somewhat protective over Palmer concerning the way others treat him, particularly Eichhorst, and has told Palmer that he doesn't have to listen to Eichhorst, nor do anything he says. She tells Palmer that Eichhorst is using him. Not long after working with Palmer, she begins to overstep her boundaries in regards to inquiring more about what's really going on. When Palmer claims he is protecting her by not telling her, she becomes angry and leaves, returning only after Palmer pleads with her.
After Coco receives the White and Palmer explains to her what is really going on, she remains with Palmer, seeming to approve of the benefit of the White, as well as Palmer's methods. It is noted that she also gained a burst of confidence afterwards, which was displayed when she stood up in retort against Eichhorst. It should also be noted that practically everything Coco says to Palmer seems to be how Palmer feels or thinks. Whether this is a sign of her manipulating him for her own gain, making him fall for her further, that is not entirely certain.
- Coco: "Mr. Eichhorst. I'm afraid I don't see you on the schedule."
Eichhorst: "That's right. That is because I am never on the schedule."
- Palmer: "Coco, I've never felt anything like this before. It's like I'm being burned alive."
Coco: "It's called heartbreak."
- Palmer: "I'm doing everything in my power to save this city, but there are forces out there working just as hard to make sure I fail. The truth is, when you're dealing with a cruel and ruthless enemy..."
Coco: "You need people on your team who can be just as ruthless."