Alaric (Rick) Saltzman had to be the adult face of The Vampire Diaries, and while he didn't always fit in, he kept the Gilbert siblings and the entire Mystic Gang together. His evolution from a grumpy lecturer to a vampire hunter and later a vampire himself evoked different emotions.
He had no permanent enemies and always approached matters with caution, which is why he made a great father figure to Elena and Jeremy. He had his shortcoming at times but always made up for them with his wisdom and experience. Having experienced more as a human and as a vampire than the entire Mystic Gang, Alaric was the sense of reason for the whole group.
"And Thank You For Putting Up With All That Wife Talk."
Unpleasantville (s01e12)
All Jenna wanted was someone to help her keep Jeremy in line, but she also had to help Rick through discussions about his deceased wife. Rick never got over the death of Isobel, and everyone that would date him afterward had a bit of a shadow over them. Alaric was romantic with Isobel, but after she left him, his spark was extinguished, leaving a shadow of his happy and romantic version seen in the flashbacks.
He never got over her for all those years, which is why he couldn't make other relationships work afterward. He still managed to get into a relationship with Jenna, but it was rocky because the both of them were emotionally distant. The same happened when he got engaged to Caroline.
"I'm Saying I Can't Be With Her And Not Tell Her."
House Guest (s02e16)
"... it's not fair to her, and that is not the type of relationship I want," he told Elena. Alaric was honest and would not be in a relationship with someone without being straightforward with them, especially after Isobel. He loved Jenna so much, that he was willing to put their relationship at risk by telling her the truth about Isobel's death.
He delayed in doing so, though, and John Gilbert managed to poison Jenna's mind, leading to their breakup just as he feared all along. Being honest still worked for Alaric in the end as they got back together. His honesty also helped him stay in a relationship with Caroline as well as staying on the right side of the Gilbert siblings.
"No, You Need To Go Home To Your Brother."
Home (s05e22)
Despite being unable to forge a lasting relationship, Alaric was fatherly and always wanted a chance to have children. When he became the legal guardian to Elena and Jeremy, he took the role so seriously that the siblings were sometimes overwhelmed by his parenting.
Jeremy was difficult to parent for Jenna and Elena, and Alaric seemed to be the only person that could get him to see sense. He was the fatherly figure that the entire Mystic Gang needed, which is why his relationship with Caroline was awkward, as he looked more like a father than a lover.
“... I Know You Don’t Love Me The Same Way.”
Gods And Monsters (s07e22)
"I will always love you..." Alaric confessed his feelings before accepting the lack of mutual feelings from Caroline. Caroline was not in love with Alaric, but that never stopped him from trying to make their family work. All of Alaric's relationships, except the Jenna one, were one-sided. He put all his effort into the relationship even though his partners failed to reciprocate.
He spent years looking for the vampire that had killed Isobel when the reality was that she had just left him. Alaric always tried to get people to buy into his line of thinking irrespective of their feelings. While his mind believed in a perfect world, reality was different, and he was detached from it.
"So I Have To Actually Die To Get A Real Apology..."
Do Not Go Gentle (s03e20)
Damon and Alaric were friends, but their relationship was complex because Alaric did all the loving while Damon did the hurting. No one seemed to care about Alaric's feelings. He had to work himself through his pain and even apologize to those that hurt him.
He discovered that Isobel had left him without explanation, but after all those years of looking to avenge her and even following her to the other side, she wouldn't apologize. Damon actually killed Alaric twice and never apologized for it until after Alaric left the other side and came back to life.
"I Was Once A Jeremy... We Learn. Eventually."
Ordinary People (s03e08)
Despite being poor at his own relationships, Alaric was always saving other people's relationships. Jeremy's relationship with Bonnie was doomed to fail because the two were incompatible as Bonnie was mature and calm while Jeremy was the exact opposite and not ready to be in any relationship.
Alaric was still determined to be the understanding father and would do anything to help Jeremy's relationship. He did help it survive for a while longer by convincing Bonnie that Jeremy was worth a second chance. His advice also helped Elena's relationships keep going despite the fallout between the Salvatore brothers.
"... Clean Slate. Now Let's Talk About Your Grades."
History Repeating (s01e09)
Alaric never kept grudges and would give people a second chance even after they had been awful. Jeremy's drug use was affecting his grades, and his academic situation looked hopeless, especially after the previous lecturer gave up on him.
Alaric, on the other hand, was determined to help him make something of his time in school despite his misbehavior. He did the same with Damon, Elena, and Stefan after they all made mistakes and even hurt him so many times. He was always a mature person that could let go of the past and see the goodness in people.
"I'd Think Twice Before I'd Trust That Dagger..."
Crying Wolf (s02e14)
"...and some ashes," Alaric advised Damon as he planned to kill Elijah with his newfound weapons. He never did anything without getting clear information on it first, which is why he was so successful as a vampire hunter. He believed in research which helped him understand people and history, making him the most informed member of the Mystic Gang.
Rick always took information seriously as opposed to Damon, who was more of the muscle than the brain in their friendship. The White Oak Daggers could kill the originals when soaked in White Oak ash, but the group couldn't fully rely on them as Damon discovered the hard way. Alaric's caution could have helped the group defeat Klaus earlier in the show.
"... That's What We Do. We Find A Way To Keep Going!"
Black Hole Sun (s06e4)
Alaric was trying to convince Jeremy that anger and resentment were not the best emotions to guide a person through difficult times. He explained to him how he had more reasons to hate Damon than Jeremy and how he always found a reason to keep going. He transferred his resilience to those around him, helping them, especially Elena, get past tragedy.
Alaric, having survived so many tragedies in his life, made him an expert at picking himself up and moving on. He encouraged Caroline throughout the unplanned pregnancy and motherhood and also taught Jeremy to be a better vampire hunter while dealing with the loss of Jenna and Elena.
"... Think I'd Leave Damon In Charge...?"
500 Year Of Solitude (s05e11)
"And never look back?" Alaric assured Jeremy, who wasn't the biggest fan of Damon's. Being friends with Damon didn't mean that Alaric fully trusted him. He understood that Damon would make mistakes because he was impulsive and would eventually land in trouble. Alaric's fatherly character was best displayed through his understanding of teenage problems and limits and then providing solutions.
He studied and understood people at a personal level and always knew everyone's strengths and weaknesses. He treated everyone, including his friends, with a sense of caution as he knew that everyone could easily give in to their inner weakness, especially when they were vampires.