User blog comment:KarinS/Ser Jorah/@comment-4018689-20110622100125

Its a reference to Dothraki Bloodrider. If you remember from episode nine when Qotho came into the tent and started arguing. Jorah Mormont told him that she is still his khaleesi and he should show her respect and then he answered "Only while the blood of my blood lives." Its basically a blood oath where you swear fidelity to your khal.