Betrayal!
"Killer Move: Oblivion!"
If Torpedum's attack on the teleportation portal at the last moment could be excused off as a mistake with terrible consequences, this Great White Shark's unprovoked attack on Sebastian revealed its animosity.
The fact that Torpedum directly used his only killer move showed that this situation already degraded to the ugliest of levels.
None of the sharks expected a betrayal at this point, not Old Mak, not the clan elders, and definitely not Sebastian. They were all shocked.
For all the time that he had spent in this world, Sebastian already got used to the notion that this was a world of cannibalism. It was either you toughen up and kill your opponent to evolve or your opponent will kill you to evolve.
When Sebastian first learned of this, he didn't pay much attention to it but with time, he was convinced that if this was all there is to Oceania, there was no way that he would be able to cope for an extended period.