Grendel is a kind, charitable man who merely wants to help other people as best he can. He can be more than a little clueless at times and is quick to jump to conclusions that may not make sense, but most people find it easy to forgive him for it. He's a feral child at heart and loves all things odd and peculiar, granting him a natural propensity for dealing with the odd creatures abundant in his post-apocalyptic world. 

Grendel grew up with his brother and half brother in Tokyo. The whole family moved to the USA long before the start of the apocalypse. Grendel was always fascinated with biology and the natural world, frequently catching insects and other small animals and keeping them for observation. When the odd beasts began appearing across the country, he took it upon himself to research them as best he could. He's typically the only person in a crowd not at all afraid of any given monster.