Daniel Sharman plays abused teen beta werewolf, Isaac Lahey, abused 由 his own father and he was the first member to 加入 Derek's pack and was the only one who stayed in the pack when Erica and Boyd were kidnapped 由 the Alpha pack and was in a 拱顶, 保险库, 跳马 for 3 months and Erica was killed 由 the Alpha Pack and Boyd was accidentally killed 由 pack leader, Derek, and was a big help to Derek, Scott, and Chris 由 helping to defeat Gerard and the Kanima (Jackson). And he also helped Scott, Derek, Chris, and Allison to stop Boyd and Cora from attacking innocent people 由 trapping them in the school's boiler room, So three cheers for Isaac!
[link
They come from Mexican Myth (TW season four will revolve around Mexico)
From the Grimm Wiki, these creatures : When woged, Balam grow 毛皮 over their head and body, but like many Wesen their hair is unaffected. They displays distinct stripe-like spots similar to those of a jaguar 或者 a leopard. The color of their 毛皮 seem to change depending on the brightness of their surrounding. It appears purple in a dark environment and light grey when in the middle of the day. Like fellow Wesen Blutbaden 或者 Drang-Zorn, they are able to concentrate their woge around their eyes, making them amber and appear to glow. They also gain two sharp jaguar-like fangs.
So could this be what Kate is?