If you've been keeping up with Warhammer lore lately, you'll be aware that the next big narrative expansion in the setting revolves around Demetrian Titus, the protagonist of the Space Marine games. He's back as Captain of the 2nd Company in his new model, but as that position was held by Captain Acheran in Warhammer 40,000: Space Marine II, there have been some concerns about Acheran's fate.
Those concerns were warranted, as in a recent post from Games Workshop explaining how Titus returned to the position of Captain, it was confirmed Acheran has met his end in the lore, alongside Chairon, who served as one of your companions in Space Marine II.
"Acheran's illustrious service came to an end upon the hive world of Trygg - a vital and seemingly loyal stronghold that safeguarded the Pyremoat System from Tyranid incursion," explains the post. "After a Munitorum survey vessel and its escort of Mordian Iron Guard disappeared, letting out a single psychic scream before vanishing without a trace, Acheran led a strike force to investigate, accompanied by his decorated Lieutenant, Brother Chairon."
After finding a horde of powerful Genestealers, Acheran, Chairon, and the other members of the strike force decided to shut the hive off from the rest of the galaxy, trapping themselves inside with the endless cultists. There they met their end, but not without clearing untold Genestealers from the Imperium and saving the entire sector from being overrun.
Safe to say, Acheran and Chairon won't be making it to Space Marine III. We'll have to see if their sacrifice is honoured in any way outside of the Warhammer Community post.