Whenever I would read "The scouring of the Shire" It would leave me frustrated thee way the characters talk about Lotho, as if he was some sort of well established antagonist.
I would always be left thinking, "I must have missed or forgotten the introductory passages", but for some reason I would never rifle back through the book to find these (imaginary) passages.
The following is the introduction we get in Book 1:
After lunch, the Sackville-Bagginses, Lobelia and her sandy-haired son, Lotho, turned up, much to Frodo's annoyance. 'Ours at last!' said Lobelia, as she stepped inside. It was not polite; nor strictly true, for the sale of Bag End did not take effect until midnight. But Lobelia can perhaps be forgiven: she had been obliged to wait about seventy-seven years longer for Bag End than she once hoped, and she was now a hundred years old. Anyway, she had come to see that nothing she had paid for had been carried off; and she wanted the keys. It took a long while to satisfy her, as she had brought a complete inventory with her and went right through it. In the end she departed with Lotho and the spare key and the promise that the other key would be left at the Gamgees' in Bagshot Row. She snorted, and showed plainly that she thought the Gamgees capable of plundering the hole during the night.
This is all we hear of Lotho until Book 6:
'I wonder what old Barliman was hinting at,' said Frodo....
'... [Something's] wrong with the Southfarthing evidently,' said Merry. 'There's a general shortage of pipe-weed.'
'Whatever it is,' said Pippin, 'Lotho will be at the bottom of it: you can be sure of that.'
'Deep in, but not at the bottom,' said Gandalf. 'You have forgotten Saruman. He began to take an interest in the Shire before Mordor did.'
How are we supposed to remember who Lotho are over the distance of 6 books? Since we have been told nothing about him, except his family relations and the colour of his hair, I would think this a bit of a tall order.
I guess we are supposed to remember that he is evil by association..?
Do you remember what your initial reaction was?
"Lotho who?" or "Of course Lotho Sackville-Baggins you scoundrel, I wonder what a sandy-haired villain like you is up to!"
Considering how important Lotho is for the faith of the Shire, it kind of annoys me that we hear nothing about him until the very end.