Nathan is a bit of an enigma to Susan. While she is happy enough to talk to him, the differences between them are rather glaring, and his forwardness in terms of approaching her has her on guard. Before Ernie told her Nathan was planning to ask her on a date, she hadn't realised his interest in her, and even now she is having her doubts about the whole thing. After getting irrationally upset with him for being mean to Theodore putting Terry and his sister at risk, she is opting to avoid him rather than chance a confrontation, although his apology has somewhat straightened out her ruffled feathers. She is convinced his big mouth will get him into trouble.
Over the past months Terry has quickly established himself as Susan's "voice of reason". Although they had only interacted sporadically over the years, it quickly became clear they are very much on the same wavelength, and they have been developing something of a friendship. Susan finds herself grateful for his companionship, concerned as she is about some of the other DA members, and with Ernie becoming more paranoid by the day she is glad to have someone she can bounce ideas off. That Terry has actually taken an interest in her personal life is surprising but welcome, although she does not realise the extent of it.
Previously to this year Susan hadn't given much thought to Lavender Brown. Girly, giggly and a boy magnet, she is everything Susan is not. Despite Lavender's sometimes questionable intellect, Susan does find herself envious of the other girl's confidence and the ease with which she seems to acquire what she wants. Now they have been doing research together for the DA, Susan is beginning to discover a different side to Lavender, and she found herself touched by the way she defended her after Molly Carmichael made some none-too-flattering comments about her person.
Susan has a great deal of respect for Neville. Being Herbology partners, they have been friendly for quite a while, and Susan realises very well he is not exactly the bumbling idiot Professor Snape always made him out to be. Although Susan didn't hesitate to re-join Dumbledore's Army, she does have some doubts about its actions and purposes. This is partly because she had a great deal of trust in Harry and it makes her nervous to not longer have him around, and party because she is afraid of putting her family at risk. Nevertheless, she is doing her best to believe in Neville's leadership abilities.
Ernie and Susan are second cousins, but with the way they act they might as well be siblings. Since they practically grew up together Ernie is one of the few people who really knows Susan. Unfortunately for her, he tends to use this knowledge to push her buttons, and while it is rare for Susan to lose her temper, nine times out of ten Ernie is the cause. Nevertheless, Susan does consider Ernie one of her dearest friends and much like he is always there for her, she will always be there for him when he needs her to. That Ernie is loud, rude, a big gossip, and can't seem to stop poking his nose into her business is irrelevant (if extremely annoying).
While it appears to anyone else Susan and Theodore are nothing more than classmates who are capable of holding the periodic polite conversation, they have been enjoying a quiet friendship for several years. What started as an occasional exchanging of books in 3rd year, when their interactions in Ancient Runes caused them to realise their mutual interest in reading, slowly developed to the point where Susan introduced him to her secret reading spot: an out-of-sight alcove on the third floor. Their companionship is a carefully balanced one, with several unspoken agreements in place. Keeping their friendship a secret is rapidly becoming essential rather than just a choice, yet neither of them is quite willing to give it up. With the war heating up, however, it is becoming increasingly difficult not to cross any lines, especially now they seem to be on opposite sides.
Sarcastic and brutally honest, Zacharias could be described as the Hufflepuff black sheep. Nevertheless, Susan has formed something of a friendship with him over the years, and he is noticeably less menacing when it comes to her, while remaining a minor, yet lovable thorn in her side. Susan goes to him when she is in need of a clear opinion or a reaction without immediately being judged, and in return she is there for him to bounce ideas off or play the listening ear. Being one of the few Hufflepuffs willing to put up with Zacharias' behaviour, Susan is sometimes stuck in the middle a bit, and she occasionally makes (weak) attempts at defending him.