Hongki once said the band would had disbanded after Wonbin's departure if it weren't for Seunghyun, and that he really saved them.
Seunghyun debuted with over 2000 antis simply for replacing Wonbin. Thanks to his hard work, improving talent (already impressive to begin with) and very likeable personality he's now accepted and greatly loved by the fandom.
Fans were accepting but wary of him when he debuted in "Bad Woman" era. Once "I Hope" era arrived everyone was smitten and he was a hit on variety shows for being hilarious and adorkable.
Seunghyun finally coming to terms that he is indeed an FT Island member and not an outsider who joined late.
(paraphrased) "Originally, this position was actually for Wonbin. For about 2 years, I thought, "Since I'm in Wonbin's position, I should do my best for him." Now my mind has changed. Now I think the position is originally for me."
Despite leaving the band with many (invalid) fighting/bullying rumours circulating, Wonbin still remains friends with everyone.
Wonbin cameo'ing on Muscle Girl as Hongki's friend from Korean made many fans happy, as well as their photo◊ after the filming. He also sang for You Are Beautiful which Hongki was in.
He's also tweeted to Seunghyun on twitter once, much to the delight of the fans who were eager to see the two of them interact and shoot down any misconceptions that the two don't get along because one replaced the other.
On the topic of Wonbin, him finally debuting as a soloist and reuniting with fans is this.
Whenever they win anything. In particular:
Their first ever music show win, which showed they truly were power rookies.
Their Best Rookie Award at an awards show, which got Minhwan bawling like a baby.
When they first won with "Love Love Love". By that stage they had not won any music shows for a few years and they didn't expect to win anything that day either. Them hiding behind everyone before the winner was announced and coming out with surprised reactions says it all. Also marks Seunghyun's first win as a member.
Members were at a fanmeeting with Japanese Primadonnas when a staff member ran on stage to inform them "Five Treasure Island" topped the Oricon Album Daily Charts and made them the first male foreign group in 42 years to do so on their debut. Cue Tears of Joy.
Hongki specifically chose to become a regular performer on Immortal Song so that the other members could back him up and play live more often and prove their live skills. It worked.
On an episode of Immortal Song where the performers were asked to bring someone to duet with them, Hongki performed with Heechul. Though he's one of the weaker singers in his group and self-conscious about it, Hongki still encouraged him and boosted his confidence.
Like the Birds and its MV. The lyrics and symbolism of the MV expresses their wish to be free like the birds and that it's possible. Perfectly describes the members' feelings and motivations.
The song was even chosen as the encore for the 2nd day of FNC Kingdom. An appropriate way to end the concert; not to mention seeing FT island members and their labelmates there running around, grinning and messing around with each other is a sight to see.
Jonghun's heartfelt speech to the fans at the end of their Summer Tour and crying because he is just so overwhelmed by their support and how far they've come.
Followed by the other members applauding him and Hongki giving him a backhug.
Their relationship with fans. No they don't pretend to be their boyfriends nor that they only belong to fans alone like most other boy groups are made to; instead they genuinely appreciate their fans, always treat them well and are always concerned for their welfare.
Their messages for Thanks To promo - especially the ones to each other.
Seunghyun tweeting a photo of him and his younger brother Sehyun when the latter started his enlistment.
At the FNC Kingdom concert before performing, labelmates CN Blue showed their gratitude for FT Island, acknowledging their success and thanking them for starting off the company hence bringing everyone where they are now. Slightly funny that Yonghwa was the one trying to say it but struggled with his Japanese so Jonghyun had to translate for him. It's especially sweet of them considering many Primadonnas assume CN Blue is always trying to bring them down and/or that Yonghwa is too arrogant to respect their legacy (of course there's no evidence of that anyways but fans being fans...) - moments like these perfectly refute these misconceptions, and is proof that they truly respect their older labelmate and certainly don't approve of some of their own fans that do look down on FTI for shallow reasons.
Members especially Jaejin and Seunghyun helping out and covering for Hongki whenever his voice condition is too poor to handle his usual load of lines.
Hongki joining Weibo was specifically for the sake of Chinese Primadonnas who could no longer access Instagram.
Hongki: Just like the sun will always shine onto the earth's surface, our pace of moving towards hope won't ever change or stop.
A simple yet touching moment at their "To The Light" tour: Hongki was quite tired so he sat down to do their talk with the fans - and all the other members sat down with him too in a cozy manner. Hongki complained they were bothering him but apparently his facial expressions said the exact opposite.
Hongki had to juggle both "Modern Farmer" filming and attending the band's Japan tours, thus not leaving much time to catch up with members. However he said that as soon as he noticed Seunghyun wasn't being himself he took the time to talk to him for hours about what was bothering him and cheering him up. Fans noticed that the next concert day Seunghyun was much more cheerful.
Seunghyun finally achieving his childhood dream of becoming an actor and starring in a movie for the first time. Of course it's a humble beginning, being an indie movie consisting of four different half-hour mini-movies with him starring in one of them - but it still means a lot to him and fans. In his interview at the press conference he is literally beaming with excitement.