In Greek mythology, Amphoterus (Ancient Greek Ἀμφότερος) is son of Alcmaeon by Callirrhoe daughter of Achelous, and brother of Acarnan. With his brother he is miraculously grown to avenge Alcmaeon's murder, slays Phegeus' house, and helps colonize Acarnania.
Adapted from Wikipedia, "Amphoterus (son of Alcmaeon)" · CC BY-SA 4.0
I.Twin avenger
Apollodorus has Callirrhoe's prayer make Amphoterus and Acarnan adults overnight. They catch Phegeus' sons at Agapenor's house dedicating the necklace, kill them, then enter the palace at Psophis and slay king Phegeus and his wife. Pursued toward Tegea they are spared; afterward they go to Delphi and from Epirus settle Acarnania.
The atlas id amphoterus-alcmaeon locks this Alcmaeonid. Other Amphoterus figures (Trojan warrior, Alexander's admiral) are unrelated.