Hildr follows closely behind Gawain, cognizant of, but not wholly in agreement with, the others' calls for diplomacy. Leave this stuff to the bard and the paladin...

Gallant will follow right behind Hildr beginning to think through a strategy to talk down the head of the sunless.

"Ready," Iris whispers, standing a bit further back from the door to let the others rush in first.

Gawain braces his shoulder against the stone door and shoves, opening it enough for them to slip through. He'll move about ten feet into the room, giving the others space to get in themselves. His eyes scan the room for anyone else present, leveling the tip of his glaive at any who move to approach.

The stone door scrapes loudly against the floor as Gawain pushes it open. You step into a large room, surprisingly bare in decoration. Two hulking statues of faceless knights kneel next to a stone throne sitting upon a raised dias on the opposite wall, facing the center of the chamber. A hole 20-foot across dominates the center of the room, the depths of which fall into darkness. In the corners you can see chests and bags overfilled with treasures, some of it coin, most of it things like candlesticks, silverware, gems, and jewelry.

A lone figure sits upon the throne, hunched over with their arm propped against their knee as if in contemplation. Their face is covered by a golden mask, and an abnormally large stirge rests on their shoulder.  

As you enter, they look up but otherwise don't move or say anything.

Calavaz shuffles in behind you all, calling out. "Brother please, you must stop this. These folk have come to put an end to the Sunless, but there is mercy in their hearts, please hear them!" 

The masked figure shifts on throne, leaning back in it and propping a leg up over the side. He still does not speak, but gestures for you to say your piece.

Gallant steps forward slowly, looking at his party as he moves. He stops right in front of the hole, looking at the god-like figure, "Galdren we come to you humbly asking, no begging, that you sure true strength and tactical smarts and leave this life of low-level banditry behind. We can imagine the impact of the barn burning was traumatic for you. Please let the blood shader end thank the gods for a new opportunity in life." 

Persuasion: 9 without adv; 14 with adv

Please help because these roles are trash!

If Gallant is stepping forward slowly, possibly Crannoc would have had time to tap him on the shoulder and cast Guidance on him?

From Guidance, add:  1 (oh well).

(Bringing Calavaz is giving you advantage, no one needs to Help)

Even with his own brother pleading, and the Guidance of Silvanus filling Gallant's words...The figure does not seem moved. Lazily, he swings his leg off the side of the throne and stands up. He draws a a weapon from his belt - a silvered shortsword with a draconic pommel and a line of black onyx along the fuller of the blade. Holding the weapon point out towards the door, you hear a gravely voice say. "Leave."

Crannoc has no intention of leaving, but he lets the others do the talking.

Instead, asking Silvanus' guidance, he continues to inspect the room to check whether this Galdren, the self-proclaimed Night Lord, is truly alone (besides the big stirge).  Or whether there are traps that might lend him confidence to order the party around, one against five (not counting Calavaz).

(Unfortunately, his lack of comfort in stone halls below ground seems to continue weighing on him and he is not at his best).

Crannoc Perception plus Guidance:  12 + 1 = 13

"Best sheathe your blade, sir," Hildr snarls. "'Tis mighty fine. Or I might add it to my collection." She steps toward Galdren meanacingly.

Charisma (Intimidation) check: 12

Gallant will say with passion while gripping his newly found crossbow. 

"Do not make use do this Galdren, please find your sanity, you are outnumbered."

Persuasion: 22

(Rolled the wrong thing in the game log but I rolled a 16 + 6 for persuasion) 

( Normally don't do back-to-back skill checks on the same thing. Trying something else like Hildr's intimidation is fine. But double persuasion rolls for the same encounter is a no. )

As Crannoc sweeps the room, nothing actively jumps out to him. There are no signs of holes in the walls or slits by which the could be ambushed. The only exit to the room lays behind them. But passively...Something about the hole in the center strikes an uneasy feeling within him. 

The masked figure steps off the throne, descending the steps of the dias. He points the blade towards the barbarian. "Come and take it."

"Brother, no!" Calavaz yells as Galdren bursts into action, preparing to charge the party.

Roll Initiative 

Gallant: 9

Can I change my persuasion to an investigation? 

Initiative: 19

The depths of the hole fall into darkness a short way down into it, as the light from the torches on the walls of the floor don't reach far enough to illuminate it. Looking down, the bottom reaches beyond the range of Gallant's darkvision. What it might be used for, he isn't sure. Some ancient sacrifice pit? A well? Around the rest of the throne room, there doesn't seem to be enough context to figure out what the hole's purpose might be.

Hildr's initiative [rolled by my, the player's, daughter, so I hope it counts]: 22 (natural 20)

Crannoc Initiative:  6

Iris Initiative: 5

Those Galdren is the first to break the peace, Hildr is much faster to react.

Initiative Order: Hildr -> Gawain