Brenden knew that he could escort Eragon, Brom, and Murtagh part of the way to Dras Leona even though he was moving farther away from his destination because within 30 minutes at a nice jog he could make it to Uru'baen. He knew Eragon, Brom, and Murtagh would be safe Brom was sensible and wise. Besides Brenden had warned Brom about Durza and had taught Brom a few spells incase they had to duel and he had placed powerful wards on all three of them with only Brom knowing. Not only all of this but, Brenden had added enough energy into Aren that it pulsed slightly but, this could only be seen with an eye at least as powerful as an elves. He also used a spell to speed up Brom's reflexes and make brom stronger than an elf. If only so that if he must duel Durza he can win but, After they all return to Farthen Dur Brenden planned on removing these spells because they could have great side effects because of the haste at which they had to be applied.
Soon he arrived at Uru'baen in order steal the eggs, he had two eggs laid by wyverns. Wyverns are foreign to Alagaesia and were extremely similar to dragons except they were bipedal with claws on their wings and they were unintelligent and depending on the species could not breathe fire. He had enchanted the eggs to replicate the minds of the baby dragons and to look like the eggs. As he covered several leagues in the span of minutes at time he soon saw Uru'baen. He then came to a stop in order to examine the citadel. He saw the tall walls coming to an end at the walls of the overhang. He watched the guards on the wall moving across. He saw the giant gate made out of Iron and steel. He saw much more and examined every detail of it for at least ten minutes. He had already thought of a plan as he finished examining the defenses.
"This is going to be a piece of cake." he said arrogantly to himself.
When night came around he started the first step of his plan,as he ran at the capitol he turned to the right and ascended the overhang until he reached the top. Then at that point he bent his knees and and held his arms out and turned into a Falcon. He then dived from the edge and fell for one hundred feet before pulling out of the dive and turning towards the citadel. Then flying at high speeds above the houses using chimneys as thermal updrafts so he could glide as far as possible without flapping his wings to preserve energy. Once he flew to an open window he landed and turned into a mouse and crawled down the drapes and ran straight for a door and he crawled directly under it and checked for guards. Once he was sure there were no guards he shapeshifted back into a human. He groaned slightly at being able to stretch his legs out more, he loathed being any type of rodent but, he supposed it was better than a bug. After a few seconds he crept down the hallways dodging patrols until he arrived around the corner from the kings personal quarters. He say the two guards and he moved faster than they could react and with his bare hands snapped their necks in order to not alert them at all.
After he deposed of their bodies he cast a spell to learn of any enchantments and possible traps there might be on the door if any but, the king tried to open. When he learned of the enchantments and traps he disabled them all after a couple of minutes with several spells. He then crept in to see what the king might have kept hidden there. Once inside he ran at full speed checking everything within the room looking for any and all secrets. Once he discovered all he could he burned into the wall with white and gold fire 'YOU ARE NOT SAFE I WILL BE YOUR DOOM...YOU CANNOT WIN...I AM MORE POWERFUL THAN YOU WILL EVER BECOME ONLY ONE THING COULD SAVE YOU AND IT IS OUT OF YOUR REACH...STRIVE FOR IT AS MUCH AS YOU DESIRE YOU WILL NEVER FIND IT...KNOW THIS I AM THE ULTIMATE LIFEFORM.'
Satisfied with the threat he left to go to the treasure room. Sadly the most direct route is straight towards through the throne room. He trekked down to the throne room all the while dodging guard patrols and enemy magicians luckily they were unable to sense his mind do to his spells he placed on himself. As he kept down to the throne room he found an open window and went to it and checked down below. What he saw pleased him greatly, it dropped to a wide open space with a small open window leading directly to the throne room. This window was too small for a human, an elf, or even a dwarf to get in but, he could easily enter as a small bird. He shapeshifted again and flew for the window. Once there he looked inside and what he saw surprised him, it was galbatorix scrying Durza and speaking to him. There were black leathery curtains that Brenden knew were the wings of Shruikan one of the largest dragons ever at a total length by his estimate of 330 ft. Brenden could see that shruikan head was resting down towards the front of the throne room, his head alone made Saphira seem diminutive. Brenden then paid attention to the conversation at hand.
"-is proving to be more resilient than we anticipated." Durza said cautiously paler than usual.
"Break the elf's mind within the week or bring her to me Durza." Galbatorix said softly and threateningly.
Durza seemed to turn even paler, if that was possible, before stammering, " Y-y-yes my lord."
Brenden smiled in his mind's eye more since he was still a bird and thought to himself, "I wonder how angry Galbatorix is going to be when Arya is rescued?"
"Now when the urgals attack Farthen Dur I want you to lead the charge and bring me Ajjahad's head." galbatorix spoke wickedly before ending the spell with swish of his hand.
Shruikan moved slightly and growled a deafening sound louder than an explosion.
Galbatorix was silent for a moment before he said, "Shruikan don't be so angry I'll get you some food soon. Now go back to sleep we have a flight in the morning."
Shruikan growled less loud than before but, the sound was still deafening.
Brenden up in his perch sat there amused wondering how they didn't know he was there. He was figuring out how to get past the window when Galbatorix left the throne room Brenden changed into a germ and floated to the crack between the window and the concrete. He floated to the ground behind the throne and changed his shape into the form of Galbatorix. Then he snuck past Shruikan into a passage that descended into the treasury. Once he arrived at the treasury he shapeshifted back into his true shape and entered the treasury. He searched the entire treasury for the eggs gathering several Rider's swords all the while, until he came across two chests one pure green the other red as wine. He searched for any spells that may lie upon the chests. Once he was satisfied with that the chests were safe he opened the red one and replaced it with the red wyvern egg. Then he swiftly replaced the Green egg with the green wyvern egg. He then placed the eggs in his pack and a started placing the chests back when he heard footsteps coming from around the corner. He quickly changed shape into something that was pure black with a black lightning bolt on his chest and a hood that obscures his whole face, he then acted like he was just pulling the chests out when he heard a voice bark, "Garjzla"
Faster than an arrow Brenden bent backwards as the bolt of lightning flew overhead, he grabbed it and hurled it back at Galbatorix and watched as it bounced of his wards. He then ran back and forth at the end of the passageway and stopped and hurled the lightning he created throwing 5 lightning bolts that arced across and removed many of his wards.
"You are a lightning master, you know spells that I do not, and I could not sense your mind, who are you?" Galbatorix asked buying time to find a visible weakness and a spell that might harm him.
"One whose magical prowess far surpasses your own." Brenden said with his voice sounding similar to a demon's, rasping with malice and amusement. "I have been in your citadel since dusk, I watched you conversing with you shade, I remained hidden from you guards for far longer than any other being in this world could have I was in your private quarters and I almost stole the dragon eggs out from under your very nose without realising I was here until I was long gone, do you truly believe that even if you manage to get past my wards you can harm me?"
Galbatorix stares at him dumbfounded that he was able to accomplish so much without being found and the fact that he almost escaped without notice, before he quickly recovered his composure and saying, "It seems I was mistaken in asking you who you are, perhaps I should have asked what you are and your name, and maybe we can come to an agreement and be allies."
"I am 'Worldcrosser', 'Nightslayer', 'Firewalker', and I am the 'Ancient One.' These are but, a few of my many titles, as for what I am that is a tale that you would never believe, just know this..." Brenden said murderously before running forwards faster than Galbatorix could even see and lifting him up by his throat, "...I AM THE FASTEST BEING ALIVE!"
Then as fast as he could run in that form, he left Uru'Baen in the dust and headed towards Ellesmera to give the eggs to The Cripple who is whole. He ran faster than even a dragon could fly crossing lakes, rivers, and plains with impunity. Once he arrived at the outskirts of the wards that protected the elven cities he changed shape back into his true shape for Oromis's benefit. Once he could pass through the wards he ran once again raced at momentous speeds until finally he reached the Crags of Telenor. He saw that Oromis and Glaedr were not there and he realized they might be flying above the forest, so he decided to leave a note and the eggs for Oromis explaining how he had recovered the eggs and who their riders would be. He then opened up a portal to the time and place where Brom, Eragon, Murtagh, and Arya would be at near the Entrance to Farthen Dur.
Author's note: I took many elements from the flash for this to conceal the identity of Brenden from Galbatorix, the form Brenden took was of Zoom from the CW Flash TV show.
I made a guess at about how long Shruikan would be based off of how large Saphira and Thorn were at the end of Inheritance. By my guess 330 feet seems a fair length because a 10 story building is 100 ft. tall and by the sounds of what they say in the book he was at least 300 ft in length. I also think 330 is a good size for him making him seem colossal but not large to the point that he is completely unrealistic in the Inheritance universe.