couriousness

[Lucyfer]

Maybe both of them didn't want to team with anyone but they met teamers (what is unfortunatelly unavoidable these days) and automatically tried to destroy them (so they started to team against team). In the end they become "friends", and since solo players are most often honorable ones, they resist to eat each other.
In the end it made them hypocrites, but still none of them wanted to actually cooperate ;p

When it comes to me, I always destroy/eat nicknames with "team" etc. in the first place when I play FFA. Then I eat the rest
Same thing, when I see a pair of teamers attacking solo player, I often shot viruses towards teamers. This actually makas me a sort of a teamer as well. But I don't start to cooperate after the teamers are gone or expeled. I just ignore any help or mass share as a "thank you for your help" from the saved guy. Suprisingly more and more people gets my point, and they give some mass back and go the opposite way.
But in the end it sometimes turns into "non aggression" pact. We don't attack each other which is against the rules of FFA. But it is still better than bloody teamers in FFA

Or in short words, they are simply trolls like ℱＩＲＥ said.