They were looking for red things. Specifically, red things that stayed red when you squished them or smashed them, because Cayde had woken Glint up in the middle of the night asking if he had any red paint, refusing to specify what he was going to use it for.
Glint didn't have any red paint.
So, now the three of them were hunting under the night sky for things that could be used to make red dye, or a red stain, or a red 'anything of the sort', as Cayde had put it. He refused to give them specifics, but when he simply said 'it's a Hunter thing we have to do', Glint grew hopeful. Not a lot of Hunters were willing to give Crow the time of day, let alone educate him on their traditions.
The exo hunted for his goal with single-minded focus, and Glint could tell that his Guardian wanted to ask for specifics, but was too uncertain to do so. Glint might have to give things a push, depending on what this was.
Eventually, with his help, they find everything they need, and the older Hunter starts the messy process of making a workable dye. Crow hovers nearby as the exo tries to make it redder, or less runny, and Glint decides to ask himself. He floats up to Cayde's shoulder as he scowls at the best result he's gotten so far, and gently taps him. His odd white eyes snap to Glint, questioning.
"He doesn't know what this is." Glint tells him quietly. The older Guardian blinked in confusion. He looks across at Crow.
"You kidding me?" Glint's Guardian shuffled in place nervously.
"No?" he answered, and Glint could feel the embarrassment rolling off of him.
"Come here." Cayde waved him over, and the awoken came to sit across from him, still embarrassed but interest piqued. The exo took a breath, tapping his knee and staring at the fire he'd been using. "It's for Amanda."
Someone might as well have opened an airlock. For about a minute the three of them just sat in silence, Glint coming to rest on Crow's shoulder. Both Hunters stared at the ground for a long while.
"It's a Hunter mark of mourning." Cayde eventually spoke up. "A stripe on the armor. A single mark on the forehead. Someone should have told you."
He offered Crow the halfway acceptable dye he'd made. The younger Hunter hesitated for a moment, but eventually dipped his fingers in and smeared a mark across his chest and forehead before Cayde did the same. The red runs down their faces like blood as the two Hunters donned the vermillion stripe.
"I think... there's a lot of things people should have told me." Crow stated eventually.
"I'll get you caught up." Cayde told him grimly, setting the rest of the dye aside. "When this stuff finally fades, you're supposed to let yourself move on."
Crow very pointedly glances at the red stripe on Cayde's cloak.
"Hey, do as I say, not as I do. Besides, that was there when I got it."