You must have seen the Demon, out there at grass: a great ugly beast with a head like a lump of rock  and teeth like tombstones. He was Father’s war horse for many years. He had – still has – a dangerous temper, and the hardest thrashing I ever got from Father was when he caught me climbing into the Demon’s paddock with the obvious intention of trying to ride him. If Father hadn’t caught me I probably wouldn’t be talking to you now; only Father and Bergil could do anything with the Demon, and even Bergil always felt himself all over when he came out of the Demon’s stall, to make sure that he still had all his limbs. A lot of people, including Mother, thought the Demon was too ugly to suit Father’s dignity, but Father didn’t care, and after we learned from Haradrim prisoners that they  believed that the Demon could wither men with his eyes and was fed on human flesh, and that no warrior of Harad would stand his ground with the Demon bearing down on him, we realised how useful the horrid beast could be.

The Demon came from Rohan, but don’t be too quick to remind any of the Rohirrim of that fact, if you go there. They pride themselves on the beauty of their horses, and the Demon did not fit the pattern. Nobody knew where he came from; there was a rumour, which may well have been true, that he was the result of some foul experiment of the wizard Saruman, to create a troll-horse. The first the Rohirrim knew of him was when mares started to disappear from the horse-herds in the foothills around Helm’s Deep. At first the disappearances were a mystery, but the herdsmen became more watchful, and soon it was certain that the troll-horse was stealing mares for a troll-herd of his own. But knowing what he was up to was a different matter from stopping him. The first man who got in his way was knocked over and trampled to rags. Another had his skull split by one of the Demon’s fore-hoofs; a third was caught in the Demon’s teeth and flung against a rock so that his back was broken. Another was killed by the mere sound of his savage neighing, or so the herdsmen said: they were beginning to think he was no flesh-and-blood horse but an evil spirit in horse’s shape. He wasn’t, of course; but men certainly died, and I wouldn’t put anything past the Demon.

In the end the herdsmen appealed to the King, and though he hated the thought of using horses as weapons against horses, he arranged an expedition to track and kill the terrible beast. We were in Meduseld at the time, so naturally Father was invited along. Equally naturally I wanted to go too, and sulked when Father refused. The only mitigating factor was that Elfwine wasn’t allowed to go either, so we sought consolation in beating each other up.

The  expedition rode away one spring morning, with all the young warriors singing and waving their spears and boasting of the great deeds they would do, according to custom, and Father rode in their midst looking thoughtful. My account of what happened next is based mostly on what old Anborn, Father’s steward, told me, and is probably boggled by Anborn’s usual attitude. Anborn looked on the Rohirrim as amiable but inexperienced children, sadly lacking in the dignity which befitted a man (by which he meant a man of Gondor), and so tended to under-estimate them. He also went through life in the firm but incompatible convictions that (1) Father could do no wrong, and (2) Father was in need of continual reproof and criticism to keep him on the right path. Father found the first conviction heart-warming and the second salutary, and so allowed Anborn to get away with a good many things that he wouldn’t have stood from anyone else. Anyway, according to Anborn the expedition frolicked along towards Helm’s Deep, and owing entirely to the rangerly skills of himself and Father, they picked up a solitary horse’s trail that, from the enormous hoof-prints, seemed to belong to the troll-horse, and followed it until nightfall, when they made camp.

Although they didn’t exactly fear an attack, they set a watch; after all, who knew what a troll-horse could do? In the middle of the night they were all roused by a yell from the one of the watchman, and there on a few hundred yards away, outlined in starlight against the black hills, was a blacker form, huge  and menacing: it was the Demon, looking down on them. Anborn thought he must have come because some fool among the Rohirrim had decided to ride a mare; the Rohirrim thought that his evil spirit had brought him to the place where he could challenge his enemies to battle.  There was a lot of stifled excitement and running around, and within minutes about ten arrows were on string and aimed at the Demon, but nobody fired and everybody looked to  King Eomer for orders. The King hesitated. He hated the idea of killing a horse, even a troll-horse; and the Demon was barely within bowshot and might not be killed outright, or even hit. And the way he just stood there was uncanny.

Then Father stepped forward, dead in line with the horse and between him and the arrows. Eomer grabbed at his elbow and hissed at him not to be a fool, and indeed it was most unlike Father to act so rashly. But he shook off Eomer’s hand and, being stricken with madness, ignored Anborn’s urgent and sensible protests (this is Anborn talking, remember) and went on walking forward. And the Demon stood still as a stone, waiting for him. The Rohirrim muttered that the troll-horse had bewitched Father and was drawing him to his death.  They were even more sure of it when Father went right up to the horse and stood face to face with him. The next moment he was on the Demon’s back, and the Demon swung round and disappeared among the rocks. That broke the spell, and the whole band rushed to mount their horses and follow, but never a track did they find, though they spent the rest of the day looking. At sundown they concluded that the troll-horse had spirited Father away from this world and that he would never be seen again. ‘And what in Middle-Earth,’ moaned King Eomer, ‘am I to say to my sister?’ Then, with the utmost reluctance and leaving a trembling party of Rohirrim to watch the fatal spot, they turned towards Meduseld.

Anborn, of course, never doubted for a moment that Father, wherever he was, was master of the situation. (I told you Anborn was sublimely inconsistent.) Hence Anborn was the only one in the party who was not surprised when they heard the thudding of hooves behind them and up came Father, riding on the Demon. Father looked as if he’d been dragged through several hedges backwards and through a considerable amount of mud, and he had the most villainous black eye anybody had ever seen, far surpassing Elfwine’s and my best efforts, which had cost King Eomer’s chief cook a fortune in raw beefsteaks. But he was riding the Demon as easily as if he were the Evenstar’s palfrey, and without any saddle or bridle, like an Elf. A murmur of terrified astonishment went up, gradually swelling into a cheer, but even this raucous human noise didn’t seem to alarm the Demon.

Father rode up to King Eomer – not too close – and asked him in his mildest voice, somewhat muffled by a cut lip,  if he, Father, could keep the horse, if Rohan really wanted to be rid of it. King Eomer gave a sort of strangled grunt that seemed to mean something like ‘Yes’, and they rode home side to side in awed silence, except when they passed by a pool of water and Father caught sight of  his own reflection and groaned and said, ‘What in Middle Earth am I to say to your sister?’

I won't tell you what Mother said, but you can probably imagine it. 

Anyway, that’s how Father earned his reputation as a Master of Horses even among the Rohirrim, and that’s how the Demon came to Ithilien to dismay our enemies and terrify us.

I wouldn’t go any closer to him than that, if I were you.