In this post I will briefly summarise developments and movements between 325-340; the summary is drawn from Behr (70-76) and Ayres (85-104).
Nov 27, 327
Constantine writes to Arius, seeking to rehabilitate him and inviting him to submit a statement of belief. Alexander of course refused, and sent Athanasius to Constantinople to oppose the whole manoeuvre.
April 17, 328
Alexander of Alexandria dies, Athanasius recalled and elected bishop. Immediate opposition from Melitian faction.
Though Arius is forgotten, the interpretation of Nicaea and homoousios becomes a live debate between 'Eusebians' and Marcellans/Alexandrians. So Asterius defends Eusebius of Nicomedia, Marcellus responds, and then Eusebius of Caesarea responds in turn (see below).
Athanasius was summoned to a council, stacked against him, whence he fled to Constantinople, and the council reinstated Arius and then deposed Athanasius. Who, in Constantinople, convinced Constantine of his innocence (on charges of violence), but a delegation from his opponents raised the accusation of a threat to the grain supply, which was enough to get him exiled to Trier on Nov 7, 335, though without either trial or deposition from office.
Eusebius of Caesarea, before his death May 30, 339, wrote two anti-Marcellan works, Against Marcellus and Ecclesiastical Theology. Marcellus of Ancyra had been deposed in July 336 for heresy; this goes some way to showing the non-Nicenes' concern about Nicaea and Marcellus' theology. Eusebius sees Marcellus' partitive exegesis leading to the non-existence of the Word before the incarnation, and so a form of Sabellianism, coupled with an adoptionistic understanding of the incarnation.
May 22, 337
Constantine dies, leaving the empire to Constantinus (Britain and Gaul; dies 340), Constantius (East) and Constans (West). The new emperors grant leave for exiled bishops to return. Constantius transfers Eusebius of Nicomedia to Constantinople, while Athanasius returns to Alexandria Nov 23, 337, but councils in Antioch, winter 337-8 and then again winter 338-9 depose him, and so April 16, 339 Athanasius heads to Rome, where he will encounter Marcellus, begin to develop an anti-Arian polemic, as well as find support among the Latin theological traditions. He finds support in Julius of Rome, who holds a council in Rome 339-40 predictably vindicating both Marcellus and Athanasius.