That an actor isn’t series regular means that he can’t appear in every episode of the season, but he CAN have full presence in an episode. For example, in ‘Follow the Leader’ –season 5-, Richard is the main character between the action in the 70’s and in the present time.

Yeah, I think the same. Great character piece with emotional
resonance that gives a sense to the way Jacob acted with the castaways and does a great job humanizing MIB. It also answers a great bunch of the greatest mysteries of the series (what is the island, what relation it has with electromagnetism, why the…

I also loved the emotional reunions on the flashsides, when
every character started to remember. But those moments didn’t justify the time we spent with conclusive stories that each character had in this purgatory: Kate running from the police, Jack with his sun (that didn’t even exist ¬¬), Sawyer and Miles as polices…

Season 4 and 5 pays off so well all the themes and character conflicts elaborated during the first three seasons, that they are the true climax
of the series. Season 6 always felt kind of an epilogue to me.

It can't be MIB, because Walt isn't dead. So I suppose that it was psychic Walt; a real shame that we didn’t get to know more about him in later seasons, when with all the flash forwards and shit he could have perfectly returned.

Capable of making Charlie sympathetic in only 40 minutes after
two seasons of being a sucker.

By season 4 they already had a clearer idea of the mythology of the
island, as Cristian aka MIB was in the cabin manipulating Locke. So the purpose was to give the idea that the MIB had been all the time in the cabin and the one that demanded help to Locke. But I’m sure that they didn’t have that idea by the time they…

I suppose that they didn’t do it because they didn’t have enough budget
to produce cool special effects of a volcano. And after seeing the crap that
Lost did when it came to special effects, I’m ok with that. But yeah, it would
have been cooler to have a volcano as the centre of the energy of the island
than a fucking…

Under my point of view, season 5 is the worst of the series because there’re too many coincidences between McNulty’s fake case and the lies of journalist Templeton. It’s a bit forced, especially considering the accuracy that ‘The Wire’ had in previous seasons. It also had a scene or two that was out of style: Omar…

And if I ask you for more episodes like Ab Aeterno? ;)

One of the things that I didn’t like of season 6 is that we spent so much time with Kate’s, Jin’s, Sayid’s etc flashsides, that didn’t provide too much neither to the characters nor the main plot; while we could have had one more flashback of Richard, Jacob, Men in Black, Widmore or the fucking origins of the Island.

And finally Locke forgives him in the purgatory. The best relation of
the whole series, without any doubt.

Not a very important answer to resolve, but its basic storytelling that
if you start any kind of plot, you need to give it some kind of closure.

How awesome would have been a Richard flashback of his time as an Other?

They had the idea that some supernatural forces commanded the island,
but I believe it wasn't until season 5 when they figured out all the Jacob-Men in Black end game. And that's ok with me, because I prefer the human approach they finally gave than if Jacob would just be a fucking spirit.

In season 1 Tony also protected Chris although he screwed up several times. He’s always had a sense of protection with the people of his family, that’s no kind of progress. In season 4, for instance, he sent Chris to a recovery centre, whereas if it had been another member of the crew he would have killed him.

He kills Christopher without hesitation and doesn't have any kind of remorse. For me that's not a guy that has improved and changed

That speech wasn't out of character: it combined perfectly D'angelo's personality with a profound metaphor about society. One of the best scenes of the series, as it has even more resonance with the tragic destiny of all three of them (D’Angelo, Wallace and Bodie). A speech is not organic and becomes didactic when…

I don't think so. The series ends with positive and negative notes; for instance, Bubbles and Namond’s closure. In both cases we get an example of how people can improve and move on.

True, that episode is awesome. But it's neither a subplot nor the series best episode.