Who is who in פרק ט"ו?

Avshalom – Son of Dovid who rebelled against Dovid.

Achitophel (Hagiloni) – Advisor of Dovid who sided with Avshalom.

Itai Hagiti – Itai was from the area of the Plishti city of Gat and the leader of six hundred men from Gat who joined Dovid as he was running away from Achitophel. Dovid tried to encourage Itai to go on his own as he was not a local person and it would be hard for him to find people who would have pity on him, however Itai swore he would remain with Dovid. (The commentators disagree as to whether or not Itai and the men from Gat were Jewish.)

Avyatar was a priest loyal to Dovid. – Avyatar came to Dovid with Tzadok and the aron. When Dovid said to bring the aron back to Jerusalem Avyatar went with it.

Tzadok was a priest loyal to Dovid. Tzadok and all the Levi’im carried the aron to Dovid as he was running away. However, Dovid told Tzadok to return the aron to Jerusalem and he hoped to see it again one day. Tzadok returned to Jerusalem.

Achima’atz – son of Tzadok loyal to Dovid.

Yehonatan – son of Avyatar loyal to Dovid.

Chushai the Arki – A friend of Dovid who appeared in torn clothing and earth on his head as he was mourning Dovid’s loss. Dovid told Chushai he would be too much of a burden for him and encouraged Chushai to return to Jerusalem together with Tzadok and Avyatar and try to thwart any plans of Achitophel against Dovid. Dovid told Chushai to tell anything he hears to Tzadok and Avyatar and to send any important message to Dovid via Achima’atz to son of Tzadok and Yehonatan the son of Avyatar.