He loved his mentor, Mags, like family, and had to watch while she sacrificed herself in the arena to save him, Katniss, and Peeta. What's more, Mags had already sacrificed herself just to be in the arena, by taking the place of Annie, the woman Finnick loves. By the end of the Games, Finnick is seriously depressed.
She clearly loved Finnick and Annie, as it was noted she basically raised Finnick, having mentored him and likely Annie as well. She made easy friends with Katniss, who admired the old woman for her bravery and selflessness.
Chia Mags kisses Finnick on the mouth to briefly let him know that this is the last time she will see him. It's her way of saying "Goodbye" but in a more affectionate way.
Also, Mags was Finnick's mentor, and most likely helped mentor Annie. They would have all lived together in the District 4 Victors' Village. Much like how Katniss, Peeta, and Haymitch became family, it is probable Mags, Annie, and Finnick did as well, so Mags may have felt a maternal kinship towards the younger two.
Finnick also cared a lot for his mentor, Mags, who had volunteered to participate in the Games, instead of Annie. Finnick was close friends with Johanna Mason and fairly good allies with Katniss, Peeta, Wiress, and Beetee.
The Life of Finnick Odair: Hunger Games Explained (From the Books)
What was Finnick's trauma?
After winning the games, Finnick was forced into prostitution by President Snow. He was blackmailed into going out with wealthy citizens of the Capitol for the safety of his loved ones, such as his District 4 sweetheart and fellow victor Annie Cresta (Stef Dawson).
While the Hunger Games film never talked about it, the Catching Fire novel explained why she could only communicate through hand gestures. Katniss briefly mentioned that a previous stroke could have caused Mags' garbled speech. However, post-traumatic stress disorder could have also caused her speech incapacity.
Given that she is willing to make the ultimate sacrifice to protect Peeta, it's safe to assume that the Morphling was committed to the rebel cause. Like the other victors, she knows the power that Katniss has as a lightning rod for the rebellion, and she knows that Katniss will not help without Peeta.
Catching Fire's Mags Flanagan was District 4's female tribute in the 75th Quarter Quell, along with male tribute, Finnick Odair. At 80-years-old, she was the oldest tribute.
How old was Mags when she won the 11th Hunger Games?
11th Hunger Games
At the age of 16, Mags became the first victor of District 4. Her skill with fish hooks and other natural skills she likely acquired from living in District 4 probably played a role in her victory.
In the 75th Hunger Games, Finnick Odair from District 4 had a token that was a gold bangle with a flame pattern. This token was first given to Haymitch Abernathy from Effie Trinket as a sign of them being a team. Haymitch gave it to Finnick to tell Katniss to make him an ally, as he could later help her in the games.
The group eventually outruns the fog except for Mags, who sacrifices herself so that Finnick can help Katniss save Peeta. They trip and tumble down a hill but eventually stop, and Katniss watches the fog approaching. It stops just before it can get to her because it is being contained by some type of force field.
What does Johanna tell Katniss about Mags and Finnick?
Johanna tells her that Mags was Finnick's mentor and half of his family. She also tells her that she was with Wiress and Beetee because of Katniss. According to Johanna, Haymitch said if she wanted to ally with Katniss, she'd have to have Wiress and Beetee with her.
After winning the games, Snow forced Finnick into prostitution and sold his body to Capitol residents to gain their trust. Finnick only agreed to take part because Snow threatened to torture his loved ones. Even though he bedded several women throughout his time as a victor, Finnick's love for Annie remained true.
Why do you think Johanna dislikes Katniss so much?
In the case of Johanna, they each hated each other because that was what the Capitol had taught them to do. They were from competing Districts, and the idea of the Games was to keep the lesser citizens of Panem distrustful of one another and unwilling to form alliances (or raise arms in war).
Finnick learned many secrets, including that Snow, in his rise to power, poisoned his adversaries but to divert suspicion often drank from the same poisoned cup followed by an antidote that only Snow used. Segments of the propo of Katniss and Finnick are aired.
Prim (Willow Shields) was an important character, as Katniss only volunteered in the games to protect her. Arguably, many viewers find that the fixation on Prim's death took away the due respect that other characters deserve. But as the films follow Katniss, Prim's absence affects her most profoundly.
Both Morphlings die during the Hunger Games in Catching Fire, after the female tribute from District 6 protects Peeta from the monkey mutations that attack the tribute. She dies in Peeta's arms while looking at the sunset.
As Katniss gets to know Finnick during the Quarter Quell, she sees he is in fact loyal, dutiful, and caring. For example, despite Mags being a burden on his chances of survival, Finnick does everything he can to keep the eighty-year-old alive because, as we learn, she was his mentor and he genuinely cares about her.
Yes, Katniss did develop an addiction to the morphling, on account of constantly being sedated with it, however, I wouldn't say that she was an addict. An addict is someone who goes to a substance (or whatever their 'poison' may be) under their own mind.
Later, the two learn President Snow considered their actions to be an act of rebellion against the Capitol. After their last interview, in which the two continue to affect their romantic feelings for one another, Peeta comes to the realization Katniss has staged her love for him all along.
Finnick rushes to resuscitate him as he knows he needs Peeta alive to keep Katniss going. Another clue that he is in on the rebel plan comes when Katniss is about to kill him with her arrow, and he tells her, "remember who the real enemy is," which is something Haymitch said to her before the games.
(Katniss recognizes her because she was also in the forest outside District 12 when the girl was captured, and she feels guilty that she did nothing to help.) As punishment, the Capitol cut out the girl's tongue and then forced her into a life of servitude as an Avox.
Peeta used the dyes to paint a picture of Rue after Katniss covered her with flowers when she died. He says he wants to hold them accountable for killing Rue, and Effie tells him that that kind of thinking is forbidden. Katniss then tells the team she hung a dummy of Seneca Crane.
The final day of training consists of the private sessions with the Gamemakers. During her session, Katniss makes a noose for a dummy and paints on it the name of "Seneca Crane," the previous Head Gamemaker.
