Is it permissible for me to perform Hajj on behalf of a young man who committed suicide, was mentally ill, addicted to drugs, and did not pray? And will Allah be angry with me if I do so?

Suicide is a major sin, but it does not expel a Muslim from the fold of Islam. As for one who abandons prayer, he is an apostate (kafir) with a major disbelief (kufr akbar); it is not permissible to supplicate for his forgiveness or to perform Hajj on his behalf.

If the person who committed suicide was mentally ill and not of sound mind, then Hajj is not obligatory for him by consensus, and it is valid for his guardian to perform Hajj on his behalf. However, if he was of sound mind, Hajj should not be performed on his behalf as a deterrent to anyone in his condition. Nevertheless, supplication, seeking forgiveness for him, and giving charity on his behalf are more beneficial.

Allah did not become angry with Noah for supplicating for his disbelieving son because he did not know the ruling at that time; rather, He forgave him. Similarly, He did not become angry with Abraham for seeking forgiveness for his father until it became clear to him that he was an enemy of Allah, at which point he disassociated himself from him.