Goli trembled so hard his snake form almost unraveled. It may seem like Aunty Jeena was only teasing, but amongst Trelops, using another Trelop to reach adulthood was a very serious issue.
One way for them to reach adulthood, naturally, was to slowly age and eventually grow into it. But this was one of the rare cases where a long lifespan worked against them. Growing into adulthood would take so long that your chances of being killed were incredibly high in the meantime.
The second method was to take over some natural landscape and grow it, but realistically speaking, it was difficult to find an unoccupied area large enough to achieve this. The third and fastest way was to forcefully encroach upon a landscape that was once occupied by a Trelop. To be clear, this was not lethal to the other Trelop, but it would naturally weaken them a lot.
