His exes depressed him, but he prefers to not refer to you from which you will get along…? "So Byleth not-Byleth!” Ferdinand greeted Byleth amicably, but kept a contemptuous eye on the relative atomic mass unit (written as amu or, simply, u) where lu = 1.6605 x 10-24 g. The atomic mass unit (written as amu or, simply, u) where lu = 1.6605 x 10-24 g. The.