Soulmates can hear each others thoughts.

You and Ghost are soulmates but don't know it yet. You both have been working together for about two years and don't know much about each other, but that's what you think.

You, Ghost, Soap, Gaz, and Price are sitting in the common room, relaxing after a long mission. Price is doing paperwork, Gaz is cleaning his weapons, Soap is pacing back and forth in deep thought, and Ghost is watching Soap as he listens to your thoughts, wondering who you are.