They landed in front of the Hog's Head less than five minutes later to find a frantic Harry barely holding it together as he sent that last group of prisoners off to Grimmauld Place by port key.
Aberforth greeted them at the door, then disappeared into his kitchen to get a treat for the thestral, leaving it open for them to come in. They found Harry in the living room with the last of the prisoners. He rushed over to them, demanding to know what had gone wrong, then pausing as he took in their appearance.
'We had to improvise a little. We couldn't find any Floo powder, it wasn't where it was last year.' She said, knowing that Harry was bursting to tell them something.
'Ron is still alive – they caught him but he's been moved to Malfoy Manor because the wards are stronger. Flitwick is there too, apparently they're hoping we'll make a rescue attempt.'
'So we have time.' Grindelwald concluded. 'You can't use someone for a trap if they're dead.'
'We need to figure out a way to break the wards, Dobby helped us last time but I bet they've closed that loophole by now.' Hermione considered. 'Gellert, you wanted to go to Nurmengard right?'
Aberforth had sent off the last of the prisoners whilst they were talking and as they were leaving, Grindelwald pulled him aside. They had a short discussion as Hermione thanked the thestral, then the pair shook hands before Grindelwald rejoined them. He took both their hands and they disappeared from Britain in a dark swirl.
They reappeared in pitch blackness, Hermione stumbled a little, disorientated by the unexpected surroundings. Grindelwald muttered a spell and blue fire flared to life in the wall sconces down a long corridor. He walked away from them, entering the fourth door on the right. Filled with trepidation, Harry and Hermione followed him.
It was a cell, the skeleton of some long dead enemy piled on the floor beneath a set of shackles. Morbidly curious, Hermione watched as he levitated the bones and exited the cell, strolling down the corridor and down the stairs to the level below. She followed him through a heavily built door and into a large circular room.
An empty trench ran around the walls of the room, ringing a platform covered in intricately carved runes. At the centre of the platform was a stone altar and with a sickening feeling, Hermione realised that she was about to witness one of the darkest forms of magic. She threw out her arm to stop Harry going past the door and they both watched in gruesome fascination as Grindelwald floated the skeleton over to the altar.
He began to chant, raising his wand up into the air above his head. Hermione thought she recognised some of the words but they had an eerie quality, twisted among many that she did not. Magic swelled in the room as the dark wizard performed his ritual, the darkness of his aura seeming to become almost physically tangible. On the altar, the skeleton began to crumble, spilling in streams of white dust over the stone plateau and down channels into the runes.
Grindelwald staggered slightly but regained his footing without pausing his spell, the skeleton continued to crumble until whitish powder had filled every crevasse of the symbols on the ground and there was only a small pile left on the altar. The dark wizard's voice rose to a crescendo and he slammed his wand down into the bone mound. It sparked like gunpowder, searing the runes in bloody crimson light. Magic thundered through the castle, the ground shaking beneath their feet as fire roared to life in the trench around the room. Grindelwald cried out and fell to his knees as the glowing runes faded and the magical maelstrom silenced. The roaring flames in the trench faded back to a gentle flicker and the dark wizard at the altar pushed himself to his feet.
The magical bond between them was pulsing with dark energy and Hermione felt violently sick. She barely made it out of the awful room with its twisted magical residue before she was emptying her stomach against the wall. Harry stayed with her, rubbing circles on her back and pulling her hair away from her face even though he looked hardly any better.
She shakily scourgified the wall and floor when she finally felt that she had nothing left to throw up. Harry patted her once more on the back and she finally looked up to see Grindelwald leaning against the closed door. He looked awkward, as if he wanted to help but didn't know how. At that particular moment, Hermione was more than happy for him to keep his distance.
'I'm sorry, I should have thought to warn you.' He apologised sincerely, but she could feel the dark magic rushing through him from their bond. She imagined he was on an unbelievable high and was touched that he was considerate enough to recognise their feelings.
'Don't worry... is there somewhere we could rest for a while?' She asked him, wishing for nothing more than a shower and a soft bed. He agreed hastily and skirted around them to show them up the stairs.
They had to climb several levels before they left the cells, passing suddenly from cold uniformity into formal living areas. He led them up a grand staircase and into what seemed to be a massive auditorium, they climbed down into the central arena and through a dark corridor. He pushed open the door at the end and they emerged into a bright, comfortable room. It was furnished in red and gold with huge floor to ceiling windows across one wall. The two side walls were lined with books and magical artifacts in glass cases.
A spectacular view of the mountains outside the window suggested that they were at a considerable height; Hermione assumed they were at the top of the dark slit up Nurmengard's front face.
'These were my private quarters. There are guest rooms through that door on the left, the rooms you can use are unlocked.' He informed them and Hermione nodded as her and Harry hurried to get out of his evil presence.
They emerged into a dark corridor, and Hermione ran her fingers along the wall until she felt a door. The first was locked but the second opened into a large, well lit room. Harry, ever the self-sacrificing gentleman, made sure she was settled on the bed, muttered some unsavoury comments about Grindelwald and left to find his own room.
She was still awake several hours later when the dark wizard came in with a steaming mug of hot chocolate. He paused awkwardly at the door until she noticed him and invited him in. He left the drink on the bedside table and retreated quickly to the furthest armchair by the window.
'I apologise, I should have warned you.' He said as she picked up the warm drink and gratefully took a sip. He made very good hot cocoa, she noted. 'Are you feeling better? I can go if you're not.' He offered.
She nodded that she was because she knew they needed to get started researching how to remove the horcrux from Harry, even though every part of her revolted against the idea of spending any time in the presence of such evil. She noticed that even though several hours had passed, the dark magic was still coursing through his body. She could feel it through the bond like a worm in the corner of her mind. She wondered fearfully if he was usually like this, whether the presence she had grown used to was just the deprived shadow of his usual self.
'Take a shower and I'll be waiting in the main room when you're ready.' He offered with a look that let her know he knew that she was lying.
She showered quickly, despite the urge to scrub her skin raw to remove the taint. Grindelwald was waiting for her in the main room, looking out through the darkened window. He'd cleared away what had been on the desk and stacked it to one side, there were several different books open instead. She looked at them pensively, dreading the knowledge that they would hold.