Chain is a live-in scientist at a secret government facility whose goal is to contain and keep secret various supernatural phenomena. She's worked at this facility for decades - so long that she responds more readily to her codename, Chain, than her actual name, and long enough that she's become jaded to just about everything the facility's ever thrown at her. Cthulu-esque creature sucked a low-level guard's brains out in front of her? Unfortunate, but bound to happen in this line of work. Horrible atrocities performed in the name of research? A necessary sacrifice.
That all changed when Alice was brought to the facility. When Chain was assigned to serve as her guardian, she was initially resistant to the idea, but the two have since formed a strong rapport. She does her best to shield Alice from the worst the facility has to offer and provide what little companionship she can. She may be a gruff and jaded chain smoker, but it turns out she does still have a soft side. She only hopes that she can keep it safe from her job.