When you first go to Scarlet Kill's main page, there are three videos, one of which ("My Dear") shows the lead singer with his face covered in blood. Between that and the name I assumed that it would be some sort of metal or hard core band.
Instead, the video for "My Dear" follows the crash that ends the video for "Don't Wake Up", where a young couple had been driving along blissfully right up until the blaze of lights and shattering glass.
That immediately reminded me of Brand New's video for "The Quiet Things That No One Ever Knows", but also many '60s ballads of young love being cut short by death. Those seemingly disparate musical moments have intersected before, like when Pearl Jam covered "Last Kiss".
Scarlett Kill falls a little closer to the 60s sound, though it does not appear that all of their songs have fatal themes. It still tends to be more melodic and earnest than punk (without sounding quite emo, either). Bands they cover include Ed Sheeran, Goo Goo Dolls, and Green Day, so still going back and forth between sentimental and punk.
Songs are well performed and the band (composed of friends and brothers) appears to be having a good time. They may still need to dig a little deeper to find their own unique sound.