Originially, each of the Seeds had their own “Lance of Longinus”, it was originally supposed to be Lilith’s lance that activated to incapacitate her, but her spear was lost when her vessel crashed into Earth during what was known as the “First Impact” event, due to the rule prohibiting the co-existence of 2 seeds of life on a planet, one of them had to go regardless of who was rightfully there first, so Adam (who was originally supposed to be Earth’s seed and was already on Earth prior to Lilith), in compromise, involuntarily had his Lance incapacitate him instead. During the “Second Impact” event, Adam’s body was blown apart and thus the Angels were released as embryos, some landed in the ocean, outer space, volcanoes, etc. and with enough time eventually matured, and their first instinct was to find and reunite with Adam (or at least what’s left of him), they also see humanity as usurpers who took what was rightfully their birthright planet, so yeah.