Having lost his home world of Krypton, Superman is very protective of Earth, and especially of Clark Kent's family and friends. This same loss, combined with the pressure of using his powers responsibly, has caused Superman to feel lonely on Earth, despite having his friends and parents. Previous encounters with people he thought to be fellow Kryptonians, Power Girl[114] (who is, in fact from the Krypton of the Earth-Two universe) and Mon-El,[115] have led to disappointment. The arrival of Supergirl, who has been confirmed to be not only from Krypton but also his cousin, has relieved this loneliness somewhat.[116] Superman's Fortress of Solitude acts as a place of solace for him in times of loneliness and despair.[68]