[2019] Actions of Mutual Friends

Osiris stood before a gate into the Infinite Forest.

Two years ago, news had reached him that one of his oldest friends was dead. Saint had been missing for ages, but the Warlock had always assumed the Titan would turn up someday. He was wrong.
He realized he was staring through a dormant gate frame and keyed a cubical device that hung at his belt to pry the doorway open.
He couldn’t save Saint from the Vex. But every day he stood vigil in the Infinite Forest to monitor simulations of the future based on their activity.
Beyond the gate, a shimmering sea of data beckoned him.
He stepped through, into the white maw of an Infinite Forest debug chamber.
“Start it up, Sagira,” he said.
“Sure you don’t want to take a break today?” she asked, unfolding above him like a crown.
“The Vex won’t.”
She considered it a moment, then the Forest shimmered around them and the white maw dimmed to half-darknes
Then pitch black. 
The floor fell away, and Osiris’s Light held him aloft, sheathed him in a thin veneer of armor.
Nothing moved. The Warlock frowned, lit a Solar spark and held it up. It illuminated nothing around him. “Did something go wrong with the sequence?”
“I just triple-checked. No,” she replied. “This is it. This is the simulation.”
He keyed his radio.
 “Go ahead, Osiris,” Ikora said.
“What’s happening out there?” he replied.
“Take your pick. We’re at war on the Moon again. The Vex attacked.”
“And?”
“We retaliated. The Undying Mind is dead.”
“How?”
“A plan. And mutual friends.”
“Our mutual friends just changed all projected futures in the Infinite Forest.”
“You don’t sound happy about that.”
 “I’ll be in touch.” He cut the transmission. “Where are we?” he asked Sagira.
“Where we always are. Simulated Mercury.”
He couldn’t even see stars.
“How far does this void reach?”
“All the way to the Traveler, for all I know.”
“Take us there.”
Osiris knew the simulation moved around him, but the typical shimmer of the Forest was gone. There was nothing to see.
“We’re here,” she confirmed, as he found gravelly purchase under his boots. He had never heard her sound so unsure of herself.
It was brighter here at the top of a windswept dune, but barely. He couldn’t see the sun in the purple twilight that hung above him. The breeze roared in his ears.
The sphere of the Traveler was gone. In its place, an obsidian monolith at least twice the size dominated the sky. In the Last City’s place was a swirling dust storm, tinged purple by the dying light.
“When does this happen?”
“The Forest predictions give a window of two or three decades, depending on a multitude of variables. With a not-insignificant chance for acceleration based on specific elements.”
“What elements?”
“Actions of mutual friends.”
“Kill the simulation. Get me to Mercury.”