Life Link

A Life Link, simply put, is a link between two people in that if one person dies, so will the other, but, both deaths have to occur at the exact time.

With Noel Vermillion becoming the Eye of the Azure, she also became an immortal. Since Terumi Yuuki was somehow able to gain a life link with Noel, neither of them can die. Ragna the Bloodedge shares a life link with Nu (v-13). A life link in top form, according to Terumi, should make the two people stronger as he comments on how Noel was not able to beat Taokaka in her story mode.