Be warned, you will probably find the end of this chapter deeply unsatisfying.
A rider arrived at the palace in a hurry one day, accompanied by the Silvan patrol that had found him on the western side of the forest some days before. He wore the Sindar-Noldor hybrid style of robes that meant he was from over the mountains—not that he could have passed for a Lórien elf with that accent, never mind his obviously non-Silvan ancestry. He introduced himself as Lindir of Rivendell in a rushed manner and asked to please see the king immediately if it was not too much trouble, and please no formalities or tours, his business was urgent. The king was currently on his throne listening to reports, requests, and complaints, and by the time Lindir got up there, several of his prominent advisors were assembled as well, plus the prince.
Lindir wasted no time in explaining his—actually Lord Elrond's—request. As Greenwood well knew, one of the Enemy's servants had risen again and formed a kingdom in the north, and now this dark entity had gathered his forces to wage war on the peoples of the west. Rivendell had been under siege for many years now, and since, after all, Greenwood could well be next if that realm fell, Elrond was sure Thranduil would send troops to aid them against Angmar—
At this, Thranduil leapt to his feet, startling Lindir. "DO NOT SPEAK THAT NAME!"
The poor confused elf tried to stammer an apology. "Lord Elrond said you had conflict with that realm in the past—"
"Does Elrond know nothing of what Greenwood suffered there?" Thranduil snarled. "Of what I lost?!"
"You do not understand, they mean to burn Rivendell to the ground—"
"Then let it burn! Begone!"
Lindir was hauled away, and the king fell heavily back into his stone-carved throne. A few moments passed in shocked silence, and then several of the attending elves spoke at once.
"My lord, Elrond has helped us in the past—"
"This is a clear strategic mistake—"
"Ada, we cannot let them—"
"SILENCE!"
They obeyed, except for Legolas. "It is not right—"
"Enough, Legolas!"
"If you will not go, I will!"
A chill settled over the platform. Thranduil stood and descended the stairs, and there was such a coldness to his expression that Legolas only stood in shock as his father took him by the arm and pulled him away.
"Thranduil...?"
The king snapped a glare over his shoulder, and Taensirion shut up.
Thranduil dragged his frightened son all the way down to the dungeons, and pressed him into a cell. "So you do not do anything foolish," he growled, and slammed the door. He spun and walked away, snapping to Taensirion and the others who stood frozen to follow.
The prince, left alone, didn't try to suppress his startled sobs.
. . . . . .
"'Las... Why would he do this?"
Legolas shook his head despondently. "He doesn't want me to get hurt, I suppose."
Tathor sighed deeply. "I guess not."
Next to the healer, Silana squished a bag between the bars. "Here, we brought you some things to make you comfortable. It's mostly food."
"Thanks." Legolas laid the bag across the stone bench he sat on without looking inside. "Do you think he will let me out soon?"
"Ada says he will let you out tomorrow, but under guard," Silana said apologetically. Feren, the fourth and last elf present, nodded. "The king is keeping the key until then," she added.
Legolas sniffed. "All right, then." He didn't respond any more to their attempts to cheer him up, and after a while they gave up and left.
"I wish we could've told him," Tathor sighed when they were out of the palace. He was the first to pull his pack out of the tangle of roots they'd hidden their supplies in.
"Someone might have heard," replied Silana. "He'll have to hear it from our families when they read our notes."
"Poor 'Las," Tathor mumbled. "Poor Firith and Ada and Nana."
"Our Nana is going to be so upset," Feren worried to Silana. "Aleinia, I mean."
"All three of our parents," she agreed. "But... are you staying?"
Feren cast a guilty glance over his shoulder, but shook his head. "No."
"No," Tathor echoed bravely. "Let's go help Elrond."
And so they set off, hurrying to catch up to Lindir.
. . . . . .
The three did indeed leave many worries in their wake, but it turned out all right in the end.
Firith was the first to find one of the notes—his brother's, resting on Tathor's pillow in their quarters—and he took it straight to his parents, who alerted the other family. Taensirion thought seriously about telling the king, but worried about Thranduil's reaction, and so an excuse was created. In fact, it was with Alagon's help that they fabricated the slightly altered record of a long-term patrol assignment in the far north; the hotheaded elf greatly disapproved of Thranduil's response and might well have signed enough records to send half the army had they asked. The king almost certainly knew what had happened, but by the time he noticed the elves in question were gone, his anger had faded considerably and he quickly changed the subject instead of pressing.
Legolas was miserable the entire time. He would have gone off after his friends in a heartbeat, but Thranduil kept a guard on him at all times (and promised to send several patrols after him if he made a run for it). Actually, it was not this that kept the prince in place so much as Taensirion and Galion's plea for him to stay, since they knew that if a rumor reached the king that something had happened to Legolas, Thranduil likely would not live long enough to determine whether it was true. Legolas obeyed, but a subtle bitterness colored his interactions with his father.
Time passed, and a few cycles of the seasons came and went. One day news reached Greenwood that Rivendell was safe, and soon after that the three elves came home, but they weren't quite the same as when they'd left.
Feren and Silana were mostly unharmed, though each had a couple of scars which suggested that hadn't been the case the whole time they were gone. They were in quite a bit of trouble, mostly for terrifying poor Aleinia, who'd already been through so much. Still, after getting hugged, thoroughly chewed out, and hugged again a few times, they were forgiven (on the condition they never ever do such a thing ever again no matter what) and life went back to normal. The main oddity was that they wouldn't tell anyone the details of their experiences.
It was Tathor who was really changed. Sure, he cried and apologized a hundred times when he saw his family—and Legolas—and he chattered on and on about Rivendell as expected, and went back to his duties as a healer the next morning. But something had changed in his manner, something about the way he held himself, head high and shoulders squared. It made those who knew him best shiver, and Felrion swore the innocent young elf had aged a thousand years. It reminded him, he said, of the difference in Sky after the War. Only Firith and Legolas noticed that the small, slender, gentle healer's two light narrow-bladed swords were as chipped and scratched as Feren and Silana's.
And so life went on, but still, something was different after Thranduil refused to send aid to Rivendell...
