Have I erred by befriending someone, who then labeled me as deviant after I insisted on helping him, and whom I subsequently initiated reconciliation with twice?

What you did, helping your friend, treating him with kindness and compassion, being patient with his harm, forgiving him, and taking the initiative to reconcile with him, is absolutely correct. "Whoever relieves a believer of a worldly distress, Allah will relieve him of a distress on the Day of Resurrection. And whoever eases the burden of a debtor, Allah will ease his burden in this world and the Hereafter. And whoever conceals a Muslim's fault, Allah will conceal his fault in this world and the Hereafter. And Allah is in the aid of His servant as long as the servant is in the aid of his brother." You have fulfilled the right of brotherhood and been an excellent companion to your friend, so continue in this manner of dealing with others.