Imma overcame this with her “sweetness”, i.e., her ability to mitigate harsh judgments. For at one point, Zeir Anpin and Imma are said to have “married”  and to have come to work in tandem on various levels. As a result, Ramchal adds in his comments, though “Zeir Anpin is intrinsically aligned with (harsh) judgment, Imma granted it a share of her intrinsic power of mitigation” when they were combined, and Zeir Anpin became more sympathetic, so to speak .
And indeed when judgment subsides, “sorrow” passes and “brotherly love” comes into play after all, in potential . In fact, that’s actually why Imma enters there, i.e., into Zeir Anpin in the world of Tikkun: in order to foster this sort of “brotherly love” among its Sephirot.
But didn’t we learn above that the source of the harsh makeup of Zeir Anpin is Imma’s own judgment element? What was it then in Imma that enabled it to be more sympathetic itself rather than harsh? Ramchal pointed out that it had been Imma’s five Gevurot that provided Zeir Anpin with its judgment aspect; thus it was Imma’s five Chassadim (kindness aspects) that granted Zeir Anpin its new kindness. For there are two “sides” — two poles — to Imma, as it has (five elements of) Chessed and (five of) Gevurah, as Ar”i points out .
 See Eitz Chaim, Sha’ar HaMochin ch. 1).
 In his comments here Ramchal ties this in once again with the various mochin of Zeir Anpin, as when it’s “immature” and experiences what we’d term “small-mindedness” as opposed to when it’s “mature” and to experience “large-mindedness” so to speak. As he explains it there, “In the stage of immaturity, only the external aspect of this aspect of Imma is granted Zeir Anpin…. But as Zeir Anpin attains mental maturity, its (trait of harsh) judgment becomes more mitigated”. See note 7 above as well as Petachim 128-129.
 See Petach 123 and Ramchal’s comments there as well as Klallim Rishonim 23.
 See Eitz Chaim 9:1 for a discussion of the five gevurot and 5 chassadim.
(c) 2013 Rabbi Yaakov Feldman
Feel free to contact me at email@example.com
AT LONG LAST! Rabbi Feldman’s translation of Maimonides’ “Eight Chapters” is available here at a discount.
You can still purchase a copy of Rabbi Feldman’s translation of “The Gates of Repentance” here at a discount as well.
Rabbi Yaakov Feldman has also translated and commented upon “The Path of the Just” and “The Duties of the Heart” (Jason Aronson Publishers).