Who are the 'We' in the Al-Khidr Story?

In S 18:74 we read: Then they set out until when they met a boy; then he killed him. He said: Have you killed a pure soul for other than a soul? You have done an abominable thing.

S 18:80-81 And as for the boy his parents were believers and we feared that he would weary them with oppression and kufr. / So we wanted their lord to change for them one better than he in zakah and closer in compassion.

Is Al-Khidr calling himself 'we'? For what reason might he be? Are 'we' Al-Khidr and Allah? Was Al-Khidr Allah? Did Allah have a lord?

Who is Allah's Lord?

In non-quranic hadith we read that his victim was predestined to be a disbeliever.

Narrated Ibn 'Abbas:

that Ubayy bin Ka'b narrated that the Prophet (ﷺ) said: "The boy that Al-Khidr killed was destined to be a disbeliever the day he was created.'"

https://sunnah.com/urn/641690 / : Jami` at-Tirmidhi 3150