Apemantus remains with Timon. Timon says he would give Apemantus a gift too if only he would be less sullen, but Apemantus says there would be no one to criticize Timon if he is bribed, and then Timon's downfall would come even faster. Timon swears he won't listen to Apemantus and departs. Apemantus says he wishes men would listen to advice more readily than they do to flattery.
Here we see Timon in action, giving away his bounty at a rate faster than he can possibly have earned it. Lords and senators attend his feast, seemingly in hopes of receiving gifts from Timon, who dispenses them with abandon, declaring that giving gifts to his friends gives him great pleasure and is part of what he believes defines friendship, so he wants nothing back.
Timon's definitions of friendship will prove to be different from those of the guests at his feast. The lords and senators are friendly to Timon so long as it benefits them, and Timon's bounty goes a long way towards making friends. Yet they are a surprisingly unsuspicious bunch, as they don't seem to doubt that Timon really wants nothing in return. So they will stick with Timon so long as he has the cash to support them, and no longer.
Yet Timon's bounty is not endless, as Flavius tries to explain to Timon. Not only has Timon used up all of his bounty, but he now gives gifts to his friends on credit, and his remaining holdings will dwindle when the debts are called due. But Timon won't listen to him, nor does he acknowledge the warnings meted out by the scornful Apemantus, who is critical of the crowd of flatterers who behave as Timon's friends only out of greed.
Apemantus's role in these proceedings is that of the observer, participating in events only to criticize them. He goes to the feast, but not as one of Timon's flatterers; in fact, Timon pointedly doesn't give him a gift after he has bestowed something on all the other guests. Apemantus is so critical of Timon he seems the farthest thing from being Timon's friend. Yet perhaps the criticism is a front for Apemantus's real feelings of friendship, which he hides behind sharp commentary, knowing Timon won't listen to his advice. After Timon's fall, Apemantus's real sentiments are never clearly delineated, but he is one of the only people to continue to support Timon once he is without riches.