How does metallic character change down a group?
Metallic character increases down a group.
Metallic character is essentially how easily an atom gives away an electron to become a cation (which metals do).
Going down a group, the atomic radius increases as well. Since the electrons in larger atoms are farther from the nucleus, the energy required to remove the most loosely-bound electron (its ionization energy) decreases.
Therefore, going down a group, since less energy is required to remove an electron, it becomes "easier", and the metallic character increases.