Hybrids and crossed strains may not give you the same phenotypes and grow/look entirely different, the purpling can occur with cooler temps. As far as the dying leaves..was probably just the need for transplanting, constant droopy leaves are also a sign of that.
I'm guessing its genetics too. Its shorter than the rest and has slightly darker and more broad leaves as well. Pretty interesting, since it was the fastest to germinate and fastest to pop through the soil.