[bena]

"Low key" is an easy enough homophone that I don't think that that will fly. I think they even used it on Supernatural at some point. Not as a name, but as a pun on the name.

Copyright is kind of loose. Gaiman and Marvel can both base a character off of the character of Norse mythology because that character is public domain. That doesn't mean either is a reference to each other. There are certain character traits that are contained within that mythology. Certain things are added by Gaiman or Marvel that are specific to their interpretations and those could be protected under copyright.

But could is not is. It really depends on how much of a deviation those details are. Or how much can be extrapolated from public characterization.

Loki and Thor being adopted brothers is probably off-limits to Gaiman as that is something Marvel invented out of whole cloth.

Loki being a secret identity of an archangel to hide from his brothers is probably off limits to both Marvel and Gaiman as that's specific to Loki's portrayal in Supernatural.

Loki being a manifestation of chaos whose power is waning and running a con out of jail is specific to Gaiman. Although deities being manifestations of belief isn't exactly a stretch itself. But him leading a new pantheon of "New Gods" is novel. That specific characterization is off limits to Marvel.

But noticing that Loki and "Low Key" sound similar, that falls squarely in the realm of possible independent discovery.