Initials on John's Boot
From Halopedia, the Halo Wiki
The Initials on Master Chief's Boots are three letters ("MRL") hidden on the bottom tread of the Master Chief's boot on Halo: Combat Evolved. They are, indeed, initials - those of Marcus R. Lehto, Halo's Art Director (and the man behind the Master Chief's skin and armor design). An easy way to see the initials is if you're on a reflective surface (Example: on Two Betrayals, while on the Control Room's bridge) just look down and on Master Chief's boot are the initials. It is even easier to view the boots in co-op mode by having your partner jump on you.
