I'm not sure if some kind of passage is supposed to come along with this, but aubergine can describe eggplants. Aubergine is a dark purple hue like that of an eggplant as well.
Grendel describes his experience with the people he observes. He states that during trivial arguments, one would kill the other and instead of the others to reprimand the killer they will detach themselves and excuse the killer. This is a violent attribute as shown by the people.
Grendel also noted that when he tried to befirend the exile one he discovered that the people were treacherous. This proves that they are untrustworthy.
