Natsu is carefree and reckless in nature, and, despite his consistent brawls with the other members of Fairy Tail, he is a fiercely loyal and protective friend. He is willing to go down fighting for his friends, regardless of how futile it might seem. Natsu has a straightforward mind, and often tackles issues with a "hands on" approach. His solution to problems often involve violence. Even when disrespected or faced with obvious hostility, Natsu rarely ever reciprocates the feelings, and often forgoes grudge-holding. He did, however, for a short time, hold a grudge against Jellal Fernandes, but eventually forgave him and considered him an ally.[20] He occasionally shows compassion for his enemies, such as when Cobra was betrayed by Brain. Natsu rarely exhibits any perverse tendencies towards the opposite sex, there only being two noted instances. The first is seen prior to the Grand Magic Games, when he is seen trying to peek, along with several other of his male Guild mates, on the women as they bathed.[22] The second is when Lucy comes crashing into him while nude, and he stares at her body, even groping her breasts for a moment.

Natsu continuously tries to prove his strength to others. At various points in time, he has challenged Erza, Laxus,Mirajane, and even Gildarts[27] (in short, all of Fairy Tail's current S-Class Mages), to fight him, albeit, he was beaten every single time. Despite his losses, Natsu bears them no ill will, as he considers everyone in the Guild to be his family. He demonstrates this attitude even towards former enemies. Natsu has even gone as far as defending Laxus from being expelled, despite his attempt at taking over the Guild. Due to his reckless nature, Natsu's fights usually ends with widespread destruction. Natsu's love of fighting has allowed him to develop a rather strategic mind, helping him to, on various occasions, find weaknesses in his opponent's techniques, or simply weaknesses his opponents themselves possess. Natsu has also defeated his opponents with pure wit, rather than brute strength. Natsu, befitting his recklessness and love of fighting, never backs out of a fight.

Natsu was very close to Lisanna, and, because of this, after her supposed death, no one in Fairy Tail mentioned her out of respect for his feelings. However, after Lisanna's return to Earth Land from Edolas, this is no longer the case.

As a Dragon Slayer, Natsu suffers from motion sickness. Natsu becomes sick from riding on any form of transportation, even if the transportation happens to be other people, as shown when he was carried by Lucy. This, however, does not apply to Happy, as he considers him family, not transportation. Natsu can become sick from looking at, or simply thinking about, any form of transportation. In spite of his naturally dense nature, Natsu is quite perceptive and understanding of his friend's feelings. After his battle with Gildarts during the S-Class Mage Promotion Trial, Natsu came to understand and accept fear, and has used this acceptance to help his guildmates and himself emotionally grow. Prior to this event, Erza’s wrath (albeit for comic relief), transportation, and the Magic Council were the only things that Natsu feared.