Somethings cannot be stopped.
It started with something small, and it might not have been noticed. Kiba turned toward him more than Hinata, no matter what was going on.
Shino noticed it.
It escalated quickly, and it should not have been commented on. Kiba found excuses to get his glasses or jacket off; Kiba accudentally brushed their hands together; Kiba cornered him and kissed him and lingered afterwards.
Shino commented on it.
It resolved easily, and it could hardly be defined. Kiba confessed love, presumably received something positive in return, and blissfully traipsed away.
Shino defined it: natural.