Is it okay to ask forgiveness for another person or is this a responsibility just for the messenger?
[42:5] The heavens above them almost shatter, out of reverence for Him, and the angels praise and glorify their Lord, and they ask forgiveness for those on earth. Absolutely, GOD is the Forgiver, Most Merciful.
It is different if someone asks us to pray for their forgiveness because they acknowledge that they did something wrong as oppose to someone who does not seek forgiveness.
[63:5] When they are told, “Come let the messenger of GOD pray for your forgiveness,” they mockingly turn their heads, and you see them repel others and act arrogantly.
[9:80] Whether you ask forgiveness for them, or do not ask forgiveness for them – even if you ask forgiveness for them seventy times – GOD will not forgive them. This is because they disbelieve in GOD and His messenger. GOD does not guide the wicked people.