Does Master Chief have any friends other than Cortana

Yes, during the attack on reach he had some squad mates. His last survived squad mate was Kelly. One of the first of the three Spartan 11 volunteers in his group. But other friends made a sacrifice, identified as James. During the first encounter inside a Covenant Cruiser, James had to detonate the charges in range of the detonation controller. So he protected the C-4 charges and died in the blast. And another Spartan 11 Jack had died on reach trying to reach an L-Z. After the escaping reach through slip-space rupture made by a covenant destroyer they promoted John Spartan 117 (at the time was a Petty Officer) into the Master Chief rank on the UNSC (United Naval Space Command) Cruiser called the Pillar of Autumn. And discovered the Forerunner rings that the covenant called Halo.