This is more a personal view than a question, but I welcome your own contributions. How come Lula lost the first round of the Brazilian elections, to then come and win the second round? (And by a bigger margin).
There are a few factors:
- A huge digital presence
For the first time, the Brazilian left decided to compete in the digital forums (whatsapp, Facebook, Twitter, even reddit I guess), with Lula's media manager Janones, creating the WhatsApp channel 'Lula's Army's to give missions to followers, like circulating videos and posts in social media.
- Presence in the streets
With a bigger digital presence, there was a bigger organization for streets presence, manifestations and public acts became huge and more frequent. There were at least three nation wide protests during this month, calling the attention of the traditional media.
- Presidential debates
After denying participation in the presidential debates, Lula came around and decided to debate Bolsonaro in the second round. Although the debates were generally seen as negative, Lula came around as more prepared and experienced, while Flávio Bolsonaro came around as arrogant, offensive, and generally a flip-flopper.
Tldr: the presence in social media was seen as something Lula could not afford to lose, the base was super charged, and he got ten more million votes than in the first round.